kernel/linux.git/lib/ratelimit.c, branch v6.6.132

ratelimit: Fix data-races in ___ratelimit().

2022-08-24T12:46:57+00:00

While reading rs->interval and rs->burst, they can be changed concurrently via sysctl (e.g. net_ratelimit_state). Thus, we need to add READ_ONCE() to their readers. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428

2019-06-05T15:37:16+00:00

Based on 1 normalized pattern(s): this file is released under the gplv2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 68 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Armijn Hemel Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190531190114.292346262@linutronix.de Signed-off-by: Greg Kroah-Hartman

lib/ratelimit.c: use deferred printk() version

2017-10-04T00:54:26+00:00

printk_ratelimit() invokes ___ratelimit() which may invoke a normal printk() (pr_warn() in this particular case) to warn about suppressed output. Given that printk_ratelimit() may be called from anywhere, that pr_warn() is dangerous - it may end up deadlocking the system. Fix ___ratelimit() by using deferred printk(). Sasha reported the following lockdep error: : Unregister pv shared memory for cpu 8 : select_fallback_rq: 3 callbacks suppressed : process 8583 (trinity-c78) no longer affine to cpu8 : : ====================================================== : WARNING: possible circular locking dependency detected : 4.14.0-rc2-next-20170927+ #252 Not tainted : ------------------------------------------------------ : migration/8/62 is trying to acquire lock: : (&port_lock_key){-.-.}, at: serial8250_console_write() : : but task is already holding lock: : (&rq->lock){-.-.}, at: sched_cpu_dying() : : which lock already depends on the new lock. : : : the existing dependency chain (in reverse order) is: : : -> #3 (&rq->lock){-.-.}: : __lock_acquire() : lock_acquire() : _raw_spin_lock() : task_fork_fair() : sched_fork() : copy_process.part.31() : _do_fork() : kernel_thread() : rest_init() : start_kernel() : x86_64_start_reservations() : x86_64_start_kernel() : verify_cpu() : : -> #2 (&p->pi_lock){-.-.}: : __lock_acquire() : lock_acquire() : _raw_spin_lock_irqsave() : try_to_wake_up() : default_wake_function() : woken_wake_function() : __wake_up_common() : __wake_up_common_lock() : __wake_up() : tty_wakeup() : tty_port_default_wakeup() : tty_port_tty_wakeup() : uart_write_wakeup() : serial8250_tx_chars() : serial8250_handle_irq.part.25() : serial8250_default_handle_irq() : serial8250_interrupt() : __handle_irq_event_percpu() : handle_irq_event_percpu() : handle_irq_event() : handle_level_irq() : handle_irq() : do_IRQ() : ret_from_intr() : native_safe_halt() : default_idle() : arch_cpu_idle() : default_idle_call() : do_idle() : cpu_startup_entry() : rest_init() : start_kernel() : x86_64_start_reservations() : x86_64_start_kernel() : verify_cpu() : : -> #1 (&tty->write_wait){-.-.}: : __lock_acquire() : lock_acquire() : _raw_spin_lock_irqsave() : __wake_up_common_lock() : __wake_up() : tty_wakeup() : tty_port_default_wakeup() : tty_port_tty_wakeup() : uart_write_wakeup() : serial8250_tx_chars() : serial8250_handle_irq.part.25() : serial8250_default_handle_irq() : serial8250_interrupt() : __handle_irq_event_percpu() : handle_irq_event_percpu() : handle_irq_event() : handle_level_irq() : handle_irq() : do_IRQ() : ret_from_intr() : native_safe_halt() : default_idle() : arch_cpu_idle() : default_idle_call() : do_idle() : cpu_startup_entry() : rest_init() : start_kernel() : x86_64_start_reservations() : x86_64_start_kernel() : verify_cpu() : : -> #0 (&port_lock_key){-.-.}: : check_prev_add() : __lock_acquire() : lock_acquire() : _raw_spin_lock_irqsave() : serial8250_console_write() : univ8250_console_write() : console_unlock() : vprintk_emit() : vprintk_default() : vprintk_func() : printk() : ___ratelimit() : __printk_ratelimit() : select_fallback_rq() : sched_cpu_dying() : cpuhp_invoke_callback() : take_cpu_down() : multi_cpu_stop() : cpu_stopper_thread() : smpboot_thread_fn() : kthread() : ret_from_fork() : : other info that might help us debug this: : : Chain exists of: : &port_lock_key --> &p->pi_lock --> &rq->lock : : Possible unsafe locking scenario: : : CPU0 CPU1 : ---- ---- : lock(&rq->lock); : lock(&p->pi_lock); : lock(&rq->lock); : lock(&port_lock_key); : : *** DEADLOCK *** : : 4 locks held by migration/8/62: : #0: (&p->pi_lock){-.-.}, at: sched_cpu_dying() : #1: (&rq->lock){-.-.}, at: sched_cpu_dying() : #2: (printk_ratelimit_state.lock){....}, at: ___ratelimit() : #3: (console_lock){+.+.}, at: vprintk_emit() : : stack backtrace: : CPU: 8 PID: 62 Comm: migration/8 Not tainted 4.14.0-rc2-next-20170927+ #252 : Call Trace: : dump_stack() : print_circular_bug() : check_prev_add() : ? add_lock_to_list.isra.26() : ? check_usage() : ? kvm_clock_read() : ? kvm_sched_clock_read() : ? sched_clock() : ? check_preemption_disabled() : __lock_acquire() : ? __lock_acquire() : ? add_lock_to_list.isra.26() : ? debug_check_no_locks_freed() : ? memcpy() : lock_acquire() : ? serial8250_console_write() : _raw_spin_lock_irqsave() : ? serial8250_console_write() : serial8250_console_write() : ? serial8250_start_tx() : ? lock_acquire() : ? memcpy() : univ8250_console_write() : console_unlock() : ? __down_trylock_console_sem() : vprintk_emit() : vprintk_default() : vprintk_func() : printk() : ? show_regs_print_info() : ? lock_acquire() : ___ratelimit() : __printk_ratelimit() : select_fallback_rq() : sched_cpu_dying() : ? sched_cpu_starting() : ? rcutree_dying_cpu() : ? sched_cpu_starting() : cpuhp_invoke_callback() : ? cpu_disable_common() : take_cpu_down() : ? trace_hardirqs_off_caller() : ? cpuhp_invoke_callback() : multi_cpu_stop() : ? __this_cpu_preempt_check() : ? cpu_stop_queue_work() : cpu_stopper_thread() : ? cpu_stop_create() : smpboot_thread_fn() : ? sort_range() : ? schedule() : ? __kthread_parkme() : kthread() : ? sort_range() : ? kthread_create_on_node() : ret_from_fork() : process 9121 (trinity-c78) no longer affine to cpu8 : smpboot: CPU 8 is now offline Link: http://lkml.kernel.org/r/20170928120405.18273-1-sergey.senozhatsky@gmail.com Fixes: 6b1d174b0c27b ("ratelimit: extend to print suppressed messages on release") Signed-off-by: Sergey Senozhatsky Reported-by: Sasha Levin Reviewed-by: Petr Mladek Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Steven Rostedt Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ratelimit: extend to print suppressed messages on release

2016-08-02T23:35:06+00:00

Extend the ratelimiting facility to print the amount of suppressed lines when it is being released. This use case is aimed at short-termed, burst-like users for which we want to output the suppressed lines stats only once, after it has been disposed of. For an example, see /dev/kmsg usage in a follow-on patch. Also, change the printk() line we issue on release to not use "callbacks" as it is misleading: we're not suppressing callbacks but printk() calls. This has been separated from a previous patch by Linus. Link: http://lkml.kernel.org/r/20160716061745.15795-2-bp@alien8.de Signed-off-by: Borislav Petkov Cc: Dave Young Cc: Franck Bui Cc: Greg Kroah-Hartman Cc: Ingo Molnar Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Uwe Kleine-König Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ratelimit: fix bug in time interval by resetting right begin time

2016-01-22T01:20:51+00:00

rs->begin in ratelimit is set in two cases. 1) when rs->begin was not initialized 2) when rs->interval was passed For case #2, current ratelimit sets the begin to 0. This incurrs improper suppression. The begin value will be set in the next ratelimit call by 1). Then the time interval check will be always false, and rs->printed will not be initialized. Although enough time passed, ratelimit may return 0 if rs->printed is not less than rs->burst. To reset interval properly, begin should be jiffies rather than 0. For an example code below: static DEFINE_RATELIMIT_STATE(mylimit, 1, 1); for (i = 1; i <= 10; i++) { if (__ratelimit(&mylimit)) printk("ratelimit test count %d\n", i); msleep(3000); } test result in the current code shows suppression even there is 3 seconds sleep. [ 78.391148] ratelimit test count 1 [ 81.295988] ratelimit test count 2 [ 87.315981] ratelimit test count 4 [ 93.336267] ratelimit test count 6 [ 99.356031] ratelimit test count 8 [ 105.376367] ratelimit test count 10 Signed-off-by: Jaewon Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib: reduce the use of module.h wherever possible

2012-03-07T20:04:04+00:00

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map them onto including export.h -- or if the file isn't even using those, then just delete the include. Fix up any implicit include dependencies that were being masked by module.h along the way. Signed-off-by: Paul Gortmaker

locking, printk: Annotate logbuf_lock as raw

2011-09-13T09:11:54+00:00

The logbuf_lock lock can be taken in atomic context and therefore cannot be preempted on -rt - annotate it. In mainline this change documents the low level nature of the lock - otherwise there's no functional difference. Lockdep and Sparse checking will work as usual. Signed-off-by: Thomas Gleixner [ merged and fixed it ] Signed-off-by: Ingo Molnar

ratelimit: fix the return value when __ratelimit() fails to acquire the lock

2010-04-07T15:38:04+00:00

The log of commit edaac8e3167501cda336231d00611bf59c164346 ("ratelimit: Fix/allow use in atomic contexts"), indicates that we want to suppress the callback when the trylock fails. Signed-off-by: Yong Zhang Cc: Ingo Molnar Cc: Christian Borntraeger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ratelimit: annotate ___ratelimit()

2010-04-07T15:38:04+00:00

To prevent from wrongly using the return value. [akpm@linux-foundation.org: fix spello] Signed-off-by: Yong Zhang Cc: Ingo Molnar Cc: Dave Young Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ratelimit: Make suppressed output messages more useful

2009-10-23T15:26:37+00:00

Today I got: [39648.224782] Registered led device: iwl-phy0::TX [40676.545099] __ratelimit: 246 callbacks suppressed [40676.545103] abcdef[23675]: segfault at 0 ... as you can see the ratelimit message contains a function prefix. Since this is always __ratelimit, this wont help much. This patch changes __ratelimit and printk_ratelimit to print the function name that calls ratelimit. This will pinpoint the responsible function, as long as not several different places call ratelimit with the same ratelimit state at the same time. In that case we catch only one random function that calls ratelimit after the wait period. Signed-off-by: Christian Borntraeger Cc: Dave Young Cc: Linus Torvalds CC: Andrew Morton LKML-Reference: <200910231458.11832.borntraeger@de.ibm.com> Signed-off-by: Ingo Molnar