aboutsummaryrefslogtreecommitdiff
path: root/kernel/printk/printk.c
AgeCommit message (Collapse)AuthorFilesLines
2025-12-05Merge tag 'soc-drivers-6.19' of ↵Linus Torvalds1-3/+8
git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc Pull SoC driver updates from Arnd Bergmann: "This is the first half of the driver changes: - A treewide interface change to the "syscore" operations for power management, as a preparation for future Tegra specific changes - Reset controller updates with added drivers for LAN969x, eic770 and RZ/G3S SoCs - Protection of system controller registers on Renesas and Google SoCs, to prevent trivially triggering a system crash from e.g. debugfs access - soc_device identification updates on Nvidia, Exynos and Mediatek - debugfs support in the ST STM32 firewall driver - Minor updates for SoC drivers on AMD/Xilinx, Renesas, Allwinner, TI - Cleanups for memory controller support on Nvidia and Renesas" * tag 'soc-drivers-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (114 commits) memory: tegra186-emc: Fix missing put_bpmp Documentation: reset: Remove reset_controller_add_lookup() reset: fix BIT macro reference reset: rzg2l-usbphy-ctrl: Fix a NULL vs IS_ERR() bug in probe reset: th1520: Support reset controllers in more subsystems reset: th1520: Prepare for supporting multiple controllers dt-bindings: reset: thead,th1520-reset: Add controllers for more subsys dt-bindings: reset: thead,th1520-reset: Remove non-VO-subsystem resets reset: remove legacy reset lookup code clk: davinci: psc: drop unused reset lookup reset: rzg2l-usbphy-ctrl: Add support for RZ/G3S SoC reset: rzg2l-usbphy-ctrl: Add support for USB PWRRDY dt-bindings: reset: renesas,rzg2l-usbphy-ctrl: Document RZ/G3S support reset: eswin: Add eic7700 reset driver dt-bindings: reset: eswin: Documentation for eic7700 SoC reset: sparx5: add LAN969x support dt-bindings: reset: microchip: Add LAN969x support soc: rockchip: grf: Add select correct PWM implementation on RK3368 soc/tegra: pmc: Add USB wake events for Tegra234 amba: tegra-ahb: Fix device leak on SMMU enable ...
2025-12-01Merge branch 'rework/threaded-printk' into for-linusPetr Mladek1-10/+7
2025-12-01Merge branch 'rework/suspend-fixes' into for-linusPetr Mladek1-17/+66
2025-12-01Merge branch 'rework/preempt-legacy-kthread' into for-linusPetr Mladek1-66/+118
2025-11-27printk: Use console_is_usable on console_unblankMarcos Paulo de Souza1-8/+4
The macro for_each_console_srcu iterates over all registered consoles. It's implied that all registered consoles have CON_ENABLED flag set, making the check for the flag unnecessary. Call console_is_usable function to fully verify if the given console is usable before calling the ->unblank callback. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://patch.msgid.link/20251121-printk-cleanup-part2-v2-3-57b8b78647f4@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-11-24printk: Avoid irq_work for printk_deferred() on suspendJohn Ogness1-1/+1
With commit ("printk: Avoid scheduling irq_work on suspend") the implementation of printk_get_console_flush_type() was modified to avoid offloading when irq_work should be blocked during suspend. Since printk uses the returned flush type to determine what flushing methods are used, this was thought to be sufficient for avoiding irq_work usage during the suspend phase. However, vprintk_emit() implements a hack to support printk_deferred(). In this hack, the returned flush type is adjusted to make sure no legacy direct printing occurs when printk_deferred() was used. Because of this hack, the legacy offloading flushing method can still be used, causing irq_work to be queued when it should not be. Adjust the vprintk_emit() hack to also consider @console_irqwork_blocked so that legacy offloading will not be chosen when irq_work should be blocked. Link: https://lore.kernel.org/lkml/87fra90xv4.fsf@jogness.linutronix.de Signed-off-by: John Ogness <john.ogness@linutronix.de> Fixes: 26873e3e7f0c ("printk: Avoid scheduling irq_work on suspend") Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-11-19printk: Avoid scheduling irq_work on suspendJohn Ogness1-15/+43
Allowing irq_work to be scheduled while trying to suspend has shown to cause problems as some architectures interpret the pending interrupts as a reason to not suspend. This became a problem for printk() with the introduction of NBCON consoles. With every printk() call, NBCON console printing kthreads are woken by queueing irq_work. This means that irq_work continues to be queued due to printk() calls late in the suspend procedure. Avoid this problem by preventing printk() from queueing irq_work once console suspending has begun. This applies to triggering NBCON and legacy deferred printing as well as klogd waiters. Since triggering of NBCON threaded printing relies on irq_work, the pr_flush() within console_suspend_all() is used to perform the final flushing before suspending consoles and blocking irq_work queueing. NBCON consoles that are not suspended (due to the usage of the "no_console_suspend" boot argument) transition to atomic flushing. Introduce a new global variable @console_irqwork_blocked to flag when irq_work queueing is to be avoided. The flag is used by printk_get_console_flush_type() to avoid allowing deferred printing and switch NBCON consoles to atomic flushing. It is also used by vprintk_emit() to avoid klogd waking. Add WARN_ON_ONCE(console_irqwork_blocked) to the irq_work queuing functions to catch any code that attempts to queue printk irq_work during the suspending/resuming procedure. Cc: stable@vger.kernel.org # 6.13.x because no drivers in 6.12.x Fixes: 6b93bb41f6ea ("printk: Add non-BKL (nbcon) console basic infrastructure") Closes: https://lore.kernel.org/lkml/DB9PR04MB8429E7DDF2D93C2695DE401D92C4A@DB9PR04MB8429.eurprd04.prod.outlook.com Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Tested-by: Sherry Sun <sherry.sun@nxp.com> Link: https://patch.msgid.link/20251113160351.113031-3-john.ogness@linutronix.de Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-11-19printk: Allow printk_trigger_flush() to flush all typesJohn Ogness1-1/+22
Currently printk_trigger_flush() only triggers legacy offloaded flushing, even if that may not be the appropriate method to flush for currently registered consoles. (The function predates the NBCON consoles.) Since commit 6690d6b52726 ("printk: Add helper for flush type logic") there is printk_get_console_flush_type(), which also considers NBCON consoles and reports all the methods of flushing appropriate based on the system state and consoles available. Update printk_trigger_flush() to use printk_get_console_flush_type() to appropriately flush registered consoles. Suggested-by: Petr Mladek <pmladek@suse.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/stable/20251113160351.113031-2-john.ogness%40linutronix.de Tested-by: Sherry Sun <sherry.sun@nxp.com> Link: https://patch.msgid.link/20251113160351.113031-2-john.ogness@linutronix.de Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-11-14syscore: Pass context data to callbacksThierry Reding1-3/+8
Several drivers can benefit from registering per-instance data along with the syscore operations. To achieve this, move the modifiable fields out of the syscore_ops structure and into a separate struct syscore that can be registered with the framework. Add a void * driver data field for drivers to store contextual data that will be passed to the syscore ops. Acked-by: Rafael J. Wysocki (Intel) <rafael@kernel.org> Signed-off-by: Thierry Reding <treding@nvidia.com>
2025-10-29printk_legacy_map: use LD_WAIT_CONFIG instead of LD_WAIT_SLEEPOleg Nesterov1-10/+7
printk_legacy_map is used to hide lock nesting violations caused by legacy drivers and is using the wrong override type. LD_WAIT_SLEEP is for always sleeping lock types such as mutex_t. LD_WAIT_CONFIG is for lock type which are sleeping while spinning on PREEMPT_RT such as spinlock_t. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://patch.msgid.link/20251026150726.GA23223@redhat.com [pmladek@suse.com: Fixed indentation.] Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-10-23printk: Use console_flush_one_record for legacy printer kthreadAndrew Murray1-6/+15
The legacy printer kthread uses console_lock and __console_flush_and_unlock to flush records to the console. This approach results in the console_lock being held for the entire duration of a flush. This can result in large waiting times for those waiting for console_lock especially where there is a large volume of records or where the console is slow (e.g. serial). This contention is observed during boot, as the call to filp_open in console_on_rootfs will delay progression to userspace until any in-flight flush is completed. Let's instead use console_flush_one_record and release/reacquire the console_lock between records. On a PocketBeagle 2, with the following boot args: "console=ttyS2,9600 initcall_debug=1 loglevel=10" Without this patch: [ 5.613166] +console_on_rootfs/filp_open [ 5.643473] mmc1: SDHCI controller on fa00000.mmc [fa00000.mmc] using ADMA 64-bit [ 5.643823] probe of fa00000.mmc returned 0 after 258244 usecs [ 5.710520] mmc1: new UHS-I speed SDR104 SDHC card at address 5048 [ 5.721976] mmcblk1: mmc1:5048 SD32G 29.7 GiB [ 5.747258] mmcblk1: p1 p2 [ 5.753324] probe of mmc1:5048 returned 0 after 40002 usecs [ 15.595240] ti_sci_pm_domains 44043000.system-controller:power-controller: sync_state() pending due to 30040000.pruss [ 15.595282] ti_sci_pm_domains 44043000.system-controller:power-controller: sync_state() pending due to e010000.watchdog [ 15.595297] ti_sci_pm_domains 44043000.system-controller:power-controller: sync_state() pending due to e000000.watchdog [ 15.595437] ti_sci_pm_domains 44043000.system-controller:power-controller: sync_state() pending due to 30300000.crc [ 146.275961] -console_on_rootfs/filp_open ... and with: [ 5.477122] +console_on_rootfs/filp_open [ 5.595814] mmc1: SDHCI controller on fa00000.mmc [fa00000.mmc] using ADMA 64-bit [ 5.596181] probe of fa00000.mmc returned 0 after 312757 usecs [ 5.662813] mmc1: new UHS-I speed SDR104 SDHC card at address 5048 [ 5.674367] mmcblk1: mmc1:5048 SD32G 29.7 GiB [ 5.699320] mmcblk1: p1 p2 [ 5.705494] probe of mmc1:5048 returned 0 after 39987 usecs [ 6.418682] -console_on_rootfs/filp_open ... ... [ 15.593509] ti_sci_pm_domains 44043000.system-controller:power-controller: sync_state() pending due to 30040000.pruss [ 15.593551] ti_sci_pm_domains 44043000.system-controller:power-controller: sync_state() pending due to e010000.watchdog [ 15.593566] ti_sci_pm_domains 44043000.system-controller:power-controller: sync_state() pending due to e000000.watchdog [ 15.593704] ti_sci_pm_domains 44043000.system-controller:power-controller: sync_state() pending due to 30300000.crc Where I've added a printk surrounding the call in console_on_rootfs to filp_open. Suggested-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Andrew Murray <amurray@thegoodpenguin.co.uk> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://patch.msgid.link/20251020-printk_legacy_thread_console_lock-v3-3-00f1f0ac055a@thegoodpenguin.co.uk [pmladek@suse.com: Fixed ordering of variable definition suggested by John.] Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-10-23printk: console_flush_one_record() code cleanupPetr Mladek1-28/+31
console_flush_one_record() and console_flush_all() duplicate several checks. They both want to tell the caller that consoles are not longer usable in this context because it has lost the lock or the lock has to be reserved for the panic CPU. Remove the duplication by changing the semantic of the function console_flush_one_record() return value and parameters. The function will return true when it is able to do the job. It means that there is at least one usable console. And the flushing was not interrupted by a takeover or panic_on_other_cpu(). Also replace the @any_usable parameter with @try_again. The @try_again parameter will be set to true when the function could do the job and at least one console made a progress. Motivation: The callers need to know when + they should continue flushing => @try_again + when the console is flushed => can_do_the_job(return) && !@try_again + when @next_seq is valid => same as flushed + when lost console_lock => @takeover The proposed change makes it clear when the function can do the job. It simplifies the answer for the other questions. Also the return value from console_flush_one_record() can be used as return value from console_flush_all(). Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://patch.msgid.link/20251020-printk_legacy_thread_console_lock-v3-2-00f1f0ac055a@thegoodpenguin.co.uk [pmladek@suse.com: Fixed type of any_usable variable reported by John] Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-10-23printk: Introduce console_flush_one_recordAndrew Murray1-59/+99
console_flush_all prints all remaining records to all usable consoles whilst its caller holds console_lock. This can result in large waiting times for those waiting for console_lock especially where there is a large volume of records or where the console is slow (e.g. serial). Let's extract the parts of this function which print a single record into a new function named console_flush_one_record. This can later be used for functions that will release and reacquire console_lock between records. This commit should not change existing functionality. Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Andrew Murray <amurray@thegoodpenguin.co.uk> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://patch.msgid.link/20251020-printk_legacy_thread_console_lock-v3-1-00f1f0ac055a@thegoodpenguin.co.uk Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-09-13panic: use angle-bracket include for panic.hJinchao Wang1-1/+1
Replace quoted includes of panic.h with `#include <linux/panic.h>` for consistency across the kernel. Link: https://lkml.kernel.org/r/20250829051312.33773-1-wangjinchao600@gmail.com Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Qianqiang Liu <qianqiang.liu@163.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-09-13panic/printk: replace other_cpu_in_panic() with panic_on_other_cpu()Jinchao Wang1-15/+4
The helper other_cpu_in_panic() duplicated logic already provided by panic_on_other_cpu(). Remove other_cpu_in_panic() and update all users to call panic_on_other_cpu() instead. This removes redundant code and makes panic handling consistent. Link: https://lkml.kernel.org/r/20250825022947.1596226-9-wangjinchao600@gmail.com Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com> Cc: Anna Schumaker <anna.schumaker@oracle.com> Cc: Baoquan He <bhe@redhat.com> Cc: "Darrick J. Wong" <djwong@kernel.org> Cc: Dave Young <dyoung@redhat.com> Cc: Doug Anderson <dianders@chromium.org> Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com> Cc: Joel Granados <joel.granados@kernel.org> Cc: John Ogness <john.ogness@linutronix.de> Cc: Kees Cook <kees@kernel.org> Cc: Li Huafei <lihuafei1@huawei.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Luo Gengkun <luogengkun@huaweicloud.com> Cc: Max Kellermann <max.kellermann@ionos.com> Cc: Nam Cao <namcao@linutronix.de> Cc: oushixiong <oushixiong@kylinos.cn> Cc: Petr Mladek <pmladek@suse.com> Cc: Qianqiang Liu <qianqiang.liu@163.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Sohil Mehta <sohil.mehta@intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Thomas Zimemrmann <tzimmermann@suse.de> Cc: Thorsten Blum <thorsten.blum@linux.dev> Cc: Ville Syrjala <ville.syrjala@linux.intel.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Yicong Yang <yangyicong@hisilicon.com> Cc: Yunhui Cui <cuiyunhui@bytedance.com> Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-09-13panic/printk: replace this_cpu_in_panic() with panic_on_this_cpu()Jinchao Wang1-13/+2
The helper this_cpu_in_panic() duplicated logic already provided by panic_on_this_cpu(). Remove this_cpu_in_panic() and switch all users to panic_on_this_cpu(). This simplifies the code and avoids having two helpers for the same check. Link: https://lkml.kernel.org/r/20250825022947.1596226-8-wangjinchao600@gmail.com Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com> Cc: Anna Schumaker <anna.schumaker@oracle.com> Cc: Baoquan He <bhe@redhat.com> Cc: "Darrick J. Wong" <djwong@kernel.org> Cc: Dave Young <dyoung@redhat.com> Cc: Doug Anderson <dianders@chromium.org> Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com> Cc: Joel Granados <joel.granados@kernel.org> Cc: John Ogness <john.ogness@linutronix.de> Cc: Kees Cook <kees@kernel.org> Cc: Li Huafei <lihuafei1@huawei.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Luo Gengkun <luogengkun@huaweicloud.com> Cc: Max Kellermann <max.kellermann@ionos.com> Cc: Nam Cao <namcao@linutronix.de> Cc: oushixiong <oushixiong@kylinos.cn> Cc: Petr Mladek <pmladek@suse.com> Cc: Qianqiang Liu <qianqiang.liu@163.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Sohil Mehta <sohil.mehta@intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Thomas Zimemrmann <tzimmermann@suse.de> Cc: Thorsten Blum <thorsten.blum@linux.dev> Cc: Ville Syrjala <ville.syrjala@linux.intel.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Yicong Yang <yangyicong@hisilicon.com> Cc: Yunhui Cui <cuiyunhui@bytedance.com> Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-09-13panic: introduce helper functions for panic stateJinchao Wang1-5/+0
Patch series "panic: introduce panic status function family", v2. This series introduces a family of helper functions to manage panic state and updates existing code to use them. Before this series, panic state helpers were scattered and inconsistent. For example, panic_in_progress() was defined in printk/printk.c, not in panic.c or panic.h. As a result, developers had to look in unexpected places to understand or re-use panic state logic. Other checks were open- coded, duplicating logic across panic, crash, and watchdog paths. The new helpers centralize the functionality in panic.c/panic.h: - panic_try_start() - panic_reset() - panic_in_progress() - panic_on_this_cpu() - panic_on_other_cpu() Patches 1–8 add the helpers and convert panic/crash and printk/nbcon code to use them. Patch 9 fixes a bug in the watchdog subsystem by skipping checks when a panic is in progress, avoiding interference with the panic CPU. Together, this makes panic state handling simpler, more discoverable, and more robust. This patch (of 9): This patch introduces four new helper functions to abstract the management of the panic_cpu variable. These functions will be used in subsequent patches to refactor existing code. The direct use of panic_cpu can be error-prone and ambiguous, as it requires manual checks to determine which CPU is handling the panic. The new helpers clarify intent: panic_try_start(): Atomically sets the current CPU as the panicking CPU. panic_reset(): Reset panic_cpu to PANIC_CPU_INVALID. panic_in_progress(): Checks if a panic has been triggered. panic_on_this_cpu(): Returns true if the current CPU is the panic originator. panic_on_other_cpu(): Returns true if a panic is on another CPU. This change lays the groundwork for improved code readability and robustness in the panic handling subsystem. Link: https://lkml.kernel.org/r/20250825022947.1596226-1-wangjinchao600@gmail.com Link: https://lkml.kernel.org/r/20250825022947.1596226-2-wangjinchao600@gmail.com Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com> Cc: Anna Schumaker <anna.schumaker@oracle.com> Cc: Baoquan He <bhe@redhat.com> Cc: "Darrick J. Wong" <djwong@kernel.org> Cc: Dave Young <dyoung@redhat.com> Cc: Doug Anderson <dianders@chromium.org> Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com> Cc: Joel Granados <joel.granados@kernel.org> Cc: John Ogness <john.ogness@linutronix.de> Cc: Kees Cook <kees@kernel.org> Cc: Li Huafei <lihuafei1@huawei.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Luo Gengkun <luogengkun@huaweicloud.com> Cc: Max Kellermann <max.kellermann@ionos.com> Cc: Nam Cao <namcao@linutronix.de> Cc: oushixiong <oushixiong@kylinos.cn> Cc: Petr Mladek <pmladek@suse.com> Cc: Qianqiang Liu <qianqiang.liu@163.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Sohil Mehta <sohil.mehta@intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Thomas Zimemrmann <tzimmermann@suse.de> Cc: Thorsten Blum <thorsten.blum@linux.dev> Cc: Ville Syrjala <ville.syrjala@linux.intel.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Yicong Yang <yangyicong@hisilicon.com> Cc: Yunhui Cui <cuiyunhui@bytedance.com> Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>b Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-06-09printk: Allow to use the printk kthread immediately even for 1st nbconPetr Mladek1-9/+11
The kthreads for nbcon consoles are created by nbcon_alloc() at the beginning of the console registration. But it currently works only for the 2nd or later nbcon console because the code checks @printk_kthreads_running. The kthread for the 1st registered nbcon console is created at the very end of register_console() by printk_kthreads_check_locked(). As a result, the entire log is replayed synchronously when the "enabled" message gets printed. It might block the boot for a long time with a slow serial console. Prevent the synchronous flush by creating the kthread even for the 1st nbcon console when it is safe (kthreads ready and no boot consoles). Also inform printk() to use the kthread by setting @printk_kthreads_running. Note that the kthreads already must be running when it is safe and this is not the 1st nbcon console. Symmetrically, clear @printk_kthreads_running when the last nbcon console was unregistered by nbcon_free(). This requires updating @have_nbcon_console before nbcon_free() gets called. Note that there is _no_ problem when the 1st nbcon console replaces boot consoles. In this case, the kthread will be started at the end of registration after the boot consoles are removed. But the console does not reply the entire log buffer in this case. Note that the flag CON_PRINTBUFFER is always cleared when the boot consoles are removed and vice versa. Closes: https://lore.kernel.org/r/20250514173514.2117832-1-mcobb@thegoodpenguin.co.uk Tested-by: Michael Cobb <mcobb@thegoodpenguin.co.uk> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://patch.msgid.link/20250604142045.253301-1-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-03-27Merge tag 'printk-for-6.15' of ↵Linus Torvalds1-11/+44
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - New option "printk.debug_non_panic_cpus" allows to store printk messages from non-panic CPUs during panic. It might be useful when panic() fails. It is disabled by default because it increases the chance to see the messages printed before panic() and on the panic-CPU. - New build option "CONFIG_NULL_TTY_DEFAULT_CONSOLE" allows to build kernel without the virtual terminal support which prefers ttynull over serial console. - Do not unblank suspended consoles. - Some code clean up. * tag 'printk-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk/panic: Add option to allow non-panic CPUs to write to the ring buffer. printk: Add an option to allow ttynull to be a default console device printk: Check CON_SUSPEND when unblanking a console printk: Rename console_start to console_resume printk: Rename console_stop to console_suspend printk: Rename resume_console to console_resume_all printk: Rename suspend_console to console_suspend_all
2025-03-27Merge branch 'for-6.15-console-suspend-api-cleanup' into for-linusPetr Mladek1-10/+20
2025-03-20printk/panic: Add option to allow non-panic CPUs to write to the ring buffer.Donghyeok Choe1-1/+19
Commit 779dbc2e78d7 ("printk: Avoid non-panic CPUs writing to ringbuffer") aimed to isolate panic-related messages. However, when panic() itself malfunctions, messages from non-panic CPUs become crucial for debugging. While commit bcc954c6caba ("printk/panic: Allow cpu backtraces to be written into ringbuffer during panic") enables non-panic CPU backtraces, it may not provide sufficient diagnostic information. Introduce the "debug_non_panic_cpus" command-line option, enabling non-panic CPU messages to be stored in the ring buffer during a panic. This also prevents discarding non-finalized messages from non-panic CPUs during console flushing, providing a more comprehensive view of system state during critical failures. Link: https://lore.kernel.org/all/Z8cLEkqLL2IOyNIj@pathway/ Signed-off-by: Donghyeok Choe <d7271.choe@samsung.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20250318022320.2428155-1-d7271.choe@samsung.com [pmladek@suse.com: Added documentation, added module_parameter, removed printk_ prefix.] Tested-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-03-17printk: Add an option to allow ttynull to be a default console deviceAdam Simonelli1-0/+5
The new option is CONFIG_NULL_TTY_DEFAULT_CONSOLE. if enabled, and CONFIG_VT is disabled, ttynull will become the default primary console device. ttynull will be the only console device usually with this option enabled. Some architectures do call add_preferred_console() which may add another console though. Motivation: Many distributions ship with CONFIG_VT enabled. On tested desktop hardware if CONFIG_VT is disabled, the default console device falls back to /dev/ttyS0 instead of /dev/tty. This could cause issues in user space, and hardware problems: 1. The user space issues include the case where /dev/ttyS0 is disconnected, and the TCGETS ioctl, which some user space libraries use as a probe to determine if a file is a tty, is called on /dev/console and fails. Programs that call isatty() on /dev/console and get an incorrect false value may skip expected logging to /dev/console. 2. The hardware issues include the case if a user has a science instrument or other device connected to the /dev/ttyS0 port, and they were to upgrade to a kernel that is disabling the CONFIG_VT option, kernel logs will then be sent to the device connected to /dev/ttyS0 unless they edit their kernel command line manually. The new CONFIG_NULL_TTY_DEFAULT_CONSOLE option will give users and distribution maintainers an option to avoid this. Disabling CONFIG_VT and enabling CONFIG_NULL_TTY_DEFAULT_CONSOLE will ensure the default kernel console behavior is not dependent on hardware configuration by default, and avoid unexpected new behavior on devices connected to the /dev/ttyS0 serial port. Reviewed-by: Petr Mladek <pmladek@suse.com> Tested-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Adam Simonelli <adamsimonelli@gmail.com> Link: https://lore.kernel.org/r/20250314160749.3286153-2-adamsimonelli@gmail.com [pmladek@suse.com: Fixed indentation of the commit message.] Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-03-11printk: Check CON_SUSPEND when unblanking a consoleMarcos Paulo de Souza1-2/+12
The commit 9e70a5e109a4 ("printk: Add per-console suspended state") introduced the CON_SUSPENDED flag for consoles. The suspended consoles will stop receiving messages, so don't unblank suspended consoles because it won't be showing anything either way. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-5-0b878577f2e6@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-03-11printk: Rename console_start to console_resumeMarcos Paulo de Souza1-2/+2
The intent of console_start was to resume a previously suspended console, so rename it accordingly. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-4-0b878577f2e6@suse.com [pmladek@suse.com: Fixed typo in the commit message. Updated also new drm_log.c.] Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-03-11printk: Rename console_stop to console_suspendMarcos Paulo de Souza1-3/+3
The intent of console_stop was in fact to suspend it, so rename the function accordingly. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-3-0b878577f2e6@suse.com [pmladek@suse.com: Fixed typo in the commit message. Updated also new drm_log.c] Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-03-11printk: Rename resume_console to console_resume_allMarcos Paulo de Souza1-1/+1
The function resume_console has a misleading name, since it resumes all consoles, so rename it accordingly. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-2-0b878577f2e6@suse.com [pmladek@suse.com: Fixed typo in the commit message.] Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-03-11printk: Rename suspend_console to console_suspend_allMarcos Paulo de Souza1-2/+2
The function suspend_console has a misleading name, since it suspends all consoles, so rename it accordingly. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-1-0b878577f2e6@suse.com [pmladek@suse.com: Fixed typo in the commit message.] Signed-off-by: Petr Mladek <pmladek@suse.com>
2025-03-04Flush console log from kernel_power_off()Paul E. McKenney1-3/+1
Kernels built with CONFIG_PREEMPT_RT=y can lose significant console output and shutdown time, which hides shutdown-time RCU issues from rcutorture. Therefore, make pr_flush() public and invoke it after then last print in kernel_power_off(). [ paulmck: Apply John Ogness feedback. ] [ paulmck: Appy Sebastian Andrzej Siewior feedback. ] [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Link: https://lore.kernel.org/r/5f743488-dc2a-4f19-bdda-cf50b9314832@paulmck-laptop Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2025-01-20Merge branch 'for-6.14-cpu_sync-fixup' into for-linusPetr Mladek1-0/+5
2024-12-16printk: Defer legacy printing when holding printk_cpu_syncJohn Ogness1-0/+5
The documentation of printk_cpu_sync_get() clearly states that the owner must never perform any activities where it waits for a CPU. For legacy printing there can be spinning on the console_lock and on the port lock. Therefore legacy printing must be deferred when holding the printk_cpu_sync. Note that in the case of emergency states, atomic consoles are not prevented from printing when printk is deferred. This is appropriate because they do not spin-wait indefinitely for other CPUs. Reported-by: Rik van Riel <riel@surriel.com> Closes: https://lore.kernel.org/r/20240715232052.73eb7fb1@imladris.surriel.com Signed-off-by: John Ogness <john.ogness@linutronix.de> Fixes: 55d6af1d6688 ("lib/nmi_backtrace: explicitly serialize banner and regs") Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20241209111746.192559-3-john.ogness@linutronix.de Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-12-12printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAXKuan-Wei Chiu1-1/+1
Shifting 1 << 31 on a 32-bit int causes signed integer overflow, which leads to undefined behavior. To prevent this, cast 1 to u32 before performing the shift, ensuring well-defined behavior. This change explicitly avoids any potential overflow by ensuring that the shift occurs on an unsigned 32-bit integer. Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Acked-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20240928113608.1438087-1-visitorckw@gmail.com Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-11-20Merge tag 'printk-for-6.13' of ↵Linus Torvalds1-9/+38
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Print more precise information about the printk log buffer memory usage. - Make sure that the sysrq title is shown on the console even when deferred. - Do not enable earlycon by `console=` which is meant to disable the default console. * tag 'printk-for-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: add dummy printk_force_console_enter/exit helpers tty: sysrq: Use printk_force_console context on __handle_sysrq printk: Introduce FORCE_CON flag printk: Improve memory usage logging during boot init: Don't proxy `console=` to earlycon
2024-11-18Merge branch 'for-6.13-force-console' into for-linusPetr Mladek1-5/+16
2024-11-11printk: Introduce FORCE_CON flagMarcos Paulo de Souza1-5/+16
Introduce FORCE_CON flag to printk. The new flag will make it possible to create a context where printk messages will never be suppressed. This mechanism will be used in the next patch to create a force_con context on sysrq handling, removing an existing workaround on the loglevel global variable. The workaround existed to make sure that sysrq header messages were sent to all consoles, but this doesn't work with deferred messages because the loglevel might be restored to its original value before a console flushes the messages. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20241105-printk-loud-con-v2-1-bd3ecdf7b0e4@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-11-05seqlock, treewide: Switch to non-raw seqcount_latch interfaceMarco Elver1-4/+5
Switch all instrumentable users of the seqcount_latch interface over to the non-raw interface. Co-developed-by: "Peter Zijlstra (Intel)" <peterz@infradead.org> Signed-off-by: "Peter Zijlstra (Intel)" <peterz@infradead.org> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20241104161910.780003-5-elver@google.com
2024-10-16printk: Improve memory usage logging during bootIsaac J. Manjarres1-4/+22
When the initial printk ring buffer size is updated, setup_log_buf() allocates a new ring buffer, as well as a set of meta-data structures for the new ring buffer. The function also emits the new size of the ring buffer, but not the size of the meta-data structures. This makes it difficult to assess how changing the log buffer size impacts memory usage during boot. For instance, increasing the ring buffer size from 512 KB to 1 MB through the command line yields an increase of 2304 KB in reserved memory at boot, while the only obvious change is the 512 KB difference in the ring buffer sizes: log_buf_len=512K: printk: log_buf_len: 524288 bytes Memory: ... (... 733252K reserved ...) log_buf_len=1M: printk: log_buf_len: 1048576 bytes Memory: ... (... 735556K reserved ...) This is because of how the size of the meta-data structures scale with the size of the ring buffer. Even when there aren't changes to the printk ring buffer size (i.e. the initial size == 1 << CONFIG_LOG_BUF_SHIFT), it is impossible to tell how much memory is consumed by the printk ring buffer during boot. Therefore, unconditionally log the sizes of the printk ring buffer and its meta-data structures, so that it's easier to understand how changing the log buffer size (either through the command line or by changing CONFIG_LOG_BUF_SHIFT) affects boot time memory usage. With the new logs, it is much easier to see exactly why the memory increased by 2304 KB: log_buf_len=512K: printk: log buffer data + meta data: 524288 + 1835008 = 2359296 bytes Memory: ... (... 733252K reserved ...) log_buf_len=1M: printk: log buffer data + meta data: 1048576 + 3670016 = 4718592 bytes Memory: ... (... 735556K reserved ...) Signed-off-by: Isaac J. Manjarres <isaacmanjarres@google.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Tested-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20240930184826.3595221-1-isaacmanjarres@google.com [pmladek@suse.com: Updated the examples in the commit message, simplified comment for default buffer.] Signed-off-by: Petr Mladek <pmladek@suse.com>
2024-09-19Merge tag 'drm-next-2024-09-19' of https://gitlab.freedesktop.org/drm/kernelLinus Torvalds1-3/+8
Pull drm updates from Dave Airlie: "This adds a couple of patches outside the drm core, all should be acked appropriately, the string and pstore ones are the main ones that come to mind. Otherwise it's the usual drivers, xe is getting enabled by default on some new hardware, we've changed the device number handling to allow more devices, and we added some optional rust code to create QR codes in the panic handler, an idea first suggested I think 10 years ago :-) string: - add mem_is_zero() core: - support more device numbers - use XArray for minor ids - add backlight constants - Split dma fence array creation into alloc and arm fbdev: - remove usage of old fbdev hooks kms: - Add might_fault() to drm_modeset_lock priming - Add dynamic per-crtc vblank configuration support dma-buf: - docs cleanup buddy: - Add start address support for trim function printk: - pass description to kmsg_dump scheduler: - Remove full_recover from drm_sched_start ttm: - Make LRU walk restartable after dropping locks - Allow direct reclaim to allocate local memory panic: - add display QR code (in rust) displayport: - mst: GUID improvements bridge: - Silence error message on -EPROBE_DEFER - analogix: Clean aup - bridge-connector: Fix double free - lt6505: Disable interrupt when powered off - tc358767: Make default DP port preemphasis configurable - lt9611uxc: require DRM_BRIDGE_ATTACH_NO_CONNECTOR - anx7625: simplify OF array handling - dw-hdmi: simplify clock handling - lontium-lt8912b: fix mode validation - nwl-dsi: fix mode vsync/hsync polarity xe: - Enable LunarLake and Battlemage support - Introducing Xe2 ccs modifiers for integrated and discrete graphics - rename xe perf to xe observation - use wb caching on DGFX for system memory - add fence timeouts - Lunar Lake graphics/media/display workarounds - Battlemage workarounds - Battlemage GSC support - GSC and HuC fw updates for LL/BM - use dma_fence_chain_free - refactor hw engine lookup and mmio access - enable priority mem read for Xe2 - Add first GuC BMG fw - fix dma-resv lock - Fix DGFX display suspend/resume - Use xe_managed for kernel BOs - Use reserved copy engine for user binds on faulting devices - Allow mixing dma-fence jobs and long-running faulting jobs - fix media TLB invalidation - fix rpm in TTM swapout path - track resources and VF state by PF i915: - Type-C programming fix for MTL+ - FBC cleanup - Calc vblank delay more accurately - On DP MST, Enable LT fallback for UHBR<->non-UHBR rates - Fix DP LTTPR detection - limit relocations to INT_MAX - fix long hangs in buddy allocator on DG2/A380 amdgpu: - Per-queue reset support - SDMA devcoredump support - DCN 4.0.1 updates - GFX12/VCN4/JPEG4 updates - Convert vbios embedded EDID to drm_edid - GFX9.3/9.4 devcoredump support - process isolation framework for GFX 9.4.3/4 - take IOMMU mappings into account for P2P DMA amdkfd: - CRIU fixes - HMM fix - Enable process isolation support for GFX 9.4.3/4 - Allow users to target recommended SDMA engines - KFD support for targetting queues on recommended SDMA engines radeon: - remove .load and drm_dev_alloc - Fix vbios embedded EDID size handling - Convert vbios embedded EDID to drm_edid - Use GEM references instead of TTM - r100 cp init cleanup - Fix potential overflows in evergreen CS offset tracking msm: - DPU: - implement DP/PHY mapping on SC8180X - Enable writeback on SM8150, SC8180X, SM6125, SM6350 - DP: - Enable widebus on all relevant chipsets - MSM8998 HDMI support - GPU: - A642L speedbin support - A615/A306/A621 support - A7xx devcoredump support ast: - astdp: Support AST2600 with VGA - Clean up HPD - Fix timeout loop for DP link training - reorganize output code by type (VGA, DP, etc) - convert to struct drm_edid - fix BMC handling for all outputs exynos: - drop stale MAINTAINERS pattern - constify struct loongson: - use GEM refcount over TTM mgag200: - Improve BMC handling - Support VBLANK intterupts - transparently support BMC outputs nouveau: - Refactor and clean up internals - Use GEM refcount over TTM's gm12u320: - convert to struct drm_edid gma500: - update i2c terms lcdif: - pixel clock fix host1x: - fix syncpoint IRQ during resume - use iommu_paging_domain_alloc() imx: - ipuv3: convert to struct drm_edid omapdrm: - improve error handling - use common helper for_each_endpoint_of_node() panel: - add support for BOE TV101WUM-LL2 plus DT bindings - novatek-nt35950: improve error handling - nv3051d: improve error handling - panel-edp: - add support for BOE NE140WUM-N6G - revert support for SDC ATNA45AF01 - visionox-vtdr6130: - improve error handling - use devm_regulator_bulk_get_const() - boe-th101mb31ig002: - Support for starry-er88577 MIPI-DSI panel plus DT - Fix porch parameter - edp: Support AOU B116XTN02.3, AUO B116XAN06.1, AOU B116XAT04.1, BOE NV140WUM-N41, BOE NV133WUM-N63, BOE NV116WHM-A4D, CMN N116BCA-EA2, CMN N116BCP-EA2, CSW MNB601LS1-4 - himax-hx8394: Support Microchip AC40T08A MIPI Display panel plus DT - ilitek-ili9806e: Support Densitron DMT028VGHMCMI-1D TFT plus DT - jd9365da: - Support Melfas lmfbx101117480 MIPI-DSI panel plus DT - Refactor for code sharing - panel-edp: fix name for HKC MB116AN01 - jd9365da: fix "exit sleep" commands - jdi-fhd-r63452: simplify error handling with DSI multi-style helpers - mantix-mlaf057we51: simplify error handling with DSI multi-style helpers - simple: - support Innolux G070ACE-LH3 plus DT bindings - support On Tat Industrial Company KD50G21-40NT-A1 plus DT bindings - st7701: - decouple DSI and DRM code - add SPI support - support Anbernic RG28XX plus DT bindings mediatek: - support alpha blending - remove cl in struct cmdq_pkt - ovl adaptor fix - add power domain binding for mediatek DPI controller renesas: - rz-du: add support for RZ/G2UL plus DT bindings rockchip: - Improve DP sink-capability reporting - dw_hdmi: Support 4k@60Hz - vop: - Support RGB display on Rockchip RK3066 - Support 4096px width sti: - convert to struct drm_edid stm: - Avoid UAF wih managed plane and CRTC helpers - Fix module owner - Fix error handling in probe - Depend on COMMON_CLK - ltdc: - Fix transparency after disabling plane - Remove unused interrupt tegra: - gr3d: improve PM domain handling - convert to struct drm_edid - Call drm_atomic_helper_shutdown() vc4: - fix PM during detect - replace DRM_ERROR() with drm_error() - v3d: simplify clock retrieval v3d: - Clean up perfmon virtio: - add DRM capset" * tag 'drm-next-2024-09-19' of https://gitlab.freedesktop.org/drm/kernel: (1326 commits) drm/xe: Fix missing conversion to xe_display_pm_runtime_resume drm/xe/xe2hpg: Add Wa_15016589081 drm/xe: Don't keep stale pointer to bo->ggtt_node drm/xe: fix missing 'xe_vm_put' drm/xe: fix build warning with CONFIG_PM=n drm/xe: Suppress missing outer rpm protection warning drm/xe: prevent potential UAF in pf_provision