user/sven/linux.git/kernel/printk, branch v5.18.3

printk: wake waiters for safe and NMI contexts

2022-06-09T08:30:01Z

[ Upstream commit 5341b93dea8c39d7612f7a227015d4b1d5cf30db ] When printk() is called from safe or NMI contexts, it will directly store the record (vprintk_store()) and then defer the console output. However, defer_console_output() only causes console printing and does not wake any waiters of new records. Wake waiters from defer_console_output() so that they also are aware of the new records from safe and NMI contexts. Fixes: 03fc7f9c99c1 ("printk/nmi: Prevent deadlock when accessing the main log buffer in NMI") Signed-off-by: John Ogness Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220421212250.565456-6-john.ogness@linutronix.de Signed-off-by: Sasha Levin

printk: add missing memory barrier to wake_up_klogd()

2022-06-09T08:30:01Z

[ Upstream commit 1f5d783094cf28b4905f51cad846eb5d1db6673e ] It is important that any new records are visible to preparing waiters before the waker checks if the wait queue is empty. Otherwise it is possible that: - there are new records available - the waker sees an empty wait queue and does not wake - the preparing waiter sees no new records and begins to wait This is exactly the problem that the function description of waitqueue_active() warns about. Use wq_has_sleeper() instead of waitqueue_active() because it includes the necessary full memory barrier. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220421212250.565456-4-john.ogness@linutronix.de Signed-off-by: Sasha Levin

Merge tag 'printk-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

2022-03-23T17:54:27Z

Pull printk updates from Petr Mladek: - Make %pK behave the same as %p for kptr_restrict == 0 also with no_hash_pointers parameter - Ignore the default console in the device tree also when console=null or console="" is used on the command line - Document console=null and console="" behavior - Prevent a deadlock and a livelock caused by console_lock in panic() - Make console_lock available for panicking CPU - Fast query for the next to-be-used sequence number - Use the expected return values in printk.devkmsg __setup handler - Use the correct atomic operations in wake_up_klogd() irq_work handler - Avoid possible unaligned access when handling %4cc printing format * tag 'printk-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: fix return value of printk.devkmsg __setup handler vsprintf: Fix %pK with kptr_restrict == 0 printk: make suppress_panic_printk static printk: Set console_set_on_cmdline=1 when __add_preferred_console() is called with user_specified == true Docs: printk: add 'console=null|""' to admin/kernel-parameters printk: use atomic updates for klogd work printk: Drop console_sem during panic printk: Avoid livelock with heavy printk during panic printk: disable optimistic spin during panic printk: Add panic_in_progress helper vsprintf: Move space out of string literals in fourcc_string() vsprintf: Fix potential unaligned access printk: ringbuffer: Improve prb_next_seq() performance

Merge branch 'rework/fast-next-seq' into for-linus

2022-03-21T13:46:19Z

Merge branch 'for-5.18-panic-deadlocks' into for-linus

2022-03-21T13:45:01Z

printk: fix return value of printk.devkmsg __setup handler

2022-03-02T08:01:37Z

If an invalid option value is used with "printk.devkmsg=", it is silently ignored. If a valid option value is used, it is honored but the wrong return value (0) is used, indicating that the command line option had an error and was not handled. This string is not added to init's environment strings due to init/main.c::unknown_bootoption() checking for a '.' in the boot option string and then considering that string to be an "Unused module parameter". Print a warning message if a bad option string is used. Always return 1 from the __setup handler to indicate that the command line option has been handled. Fixes: 750afe7babd1 ("printk: add kernel parameter to control writes to /dev/kmsg") Signed-off-by: Randy Dunlap Reported-by: Igor Zhbanov Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Cc: Borislav Petkov Cc: Andrew Morton Cc: Petr Mladek Cc: Sergey Senozhatsky Cc: Steven Rostedt Cc: John Ogness Reviewed-by: John Ogness Reviewed-by: Sergey Senozhatsky Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220228220556.23484-1-rdunlap@infradead.org

printk: make suppress_panic_printk static

2022-02-21T15:55:07Z

This symbol is not used outside of printk.c, so marks it static. Fix the following sparse warning: kernel/printk/printk.c:100:19: warning: symbol 'suppress_panic_printk' was not declared. Should it be static? Reported-by: Abaci Robot Signed-off-by: Jiapeng Chong Reviewed-by: Sergey Senozhatsky Reviewed-by: Miguel Ojeda Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220216031957.9761-1-jiapeng.chong@linux.alibaba.com

printk: Set console_set_on_cmdline=1 when __add_preferred_console() is called with user_specified == true

2022-02-21T14:52:08Z

In case of using console="" or console=null set console_set_on_cmdline=1 to disable "stdout-path" node from DT. We basically need to set it every time when __add_preferred_console() is called with parameter 'user_specified' set. Therefore we can move setting it into a helper function that is called from __add_preferred_console(). Suggested-by: Petr Mladek Signed-off-by: Andre Kalb Reviewed-by: Petr Mladek Reviewed-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/YgzU4ho8l6XapyG2@pc6682

printk: use atomic updates for klogd work

2022-02-15T15:10:55Z

The per-cpu @printk_pending variable can be updated from sleepable contexts, such as: get_random_bytes() warn_unseeded_randomness() printk_deferred() defer_console_output() and can be updated from interrupt contexts, such as: handle_irq_event_percpu() __irq_wake_thread() wake_up_process() try_to_wake_up() select_task_rq() select_fallback_rq() printk_deferred() defer_console_output() and can be updated from NMI contexts, such as: vprintk() if (in_nmi()) defer_console_output() Therefore the atomic variant of the updating functions must be used. Replace __this_cpu_xchg() with this_cpu_xchg(). Replace __this_cpu_or() with this_cpu_or(). Reported-by: Sebastian Andrzej Siewior Signed-off-by: John Ogness Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/87iltld4ue.fsf@jogness.linutronix.de

printk: Drop console_sem during panic

2022-02-14T12:39:20Z

If another CPU is in panic, we are about to be halted. Try to gracefully abandon the console_sem, leaving it free for the panic CPU to grab. Suggested-by: Petr Mladek Signed-off-by: Stephen Brennan Reviewed-by: Petr Mladek Reviewed-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220202171821.179394-5-stephen.s.brennan@oracle.com