kernel/linux.git/include/linux/notifier.h, branch v6.6.132

srcu,notifier: Remove #ifdefs in favor of SRCU Tiny srcu_usage

2023-08-16T21:27:01+00:00

This commit removes two #ifdef directives from include/linux/notifier.h by causing SRCU Tiny to provide a dummy srcu_usage structure and a dummy __SRCU_USAGE_INIT() macro. Suggested-by: Linus Torvalds Cc: Matthias Brugger Cc: "Rafael J. Wysocki" Cc: "Michał Mirosław" Cc: Dmitry Osipenko Cc: Sachin Sant Cc: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney

notifier: Initialize new struct srcu_usage field

2023-06-07T20:42:02+00:00

In commit 95433f726301 ("srcu: Begin offloading srcu_struct fields to srcu_update"), a new struct srcu_usage field was added, but was not properly initialized. This led to a "spinlock bad magic" BUG when the SRCU notifier was ever used. This was observed in the MediaTek CCI devfreq driver on next-20230525. The trimmed stack trace is as follows: BUG: spinlock bad magic on CPU#4, swapper/0/1 lock: 0xffffff80ff529ac0, .magic: 00000000, .owner: /-1, .owner_cpu: 0 Call trace: spin_bug+0xa4/0xe8 do_raw_spin_lock+0xec/0x120 _raw_spin_lock_irqsave+0x78/0xb8 synchronize_srcu+0x3c/0x168 srcu_notifier_chain_unregister+0x5c/0xa0 cpufreq_unregister_notifier+0x94/0xe0 devfreq_passive_event_handler+0x7c/0x3e0 devfreq_remove_device+0x48/0xe8 Add __SRCU_USAGE_INIT() to SRCU_NOTIFIER_INIT() so that srcu_usage gets initialized properly. Reported-by: Jon Hunter Fixes: 95433f726301 ("srcu: Begin offloading srcu_struct fields to srcu_update") Signed-off-by: Chen-Yu Tsai Tested-by: AngeloGioacchino Del Regno Cc: Matthias Brugger Cc: "Rafael J. Wysocki" Cc: "Michał Mirosław" Cc: Dmitry Osipenko Cc: Sachin Sant Cc: Joel Fernandes (Google) Acked-by: Zqiang Signed-off-by: Paul E. McKenney

srcu: Begin offloading srcu_struct fields to srcu_update

2023-04-04T15:35:34+00:00

The current srcu_struct structure is on the order of 200 bytes in size (depending on architecture and .config), which is much better than the old-style 26K bytes, but still all too inconvenient when one is trying to achieve good cache locality on a fastpath involving SRCU readers. However, only a few fields in srcu_struct are used by SRCU readers. The remaining fields could be offloaded to a new srcu_update structure, thus shrinking the srcu_struct structure down to a few tens of bytes. This commit begins this noble quest, a quest that is complicated by open-coded initialization of the srcu_struct within the srcu_notifier_head structure. This complication is addressed by updating the srcu_notifier_head structure's open coding, given that there does not appear to be a straightforward way of abstracting that initialization. This commit moves only the ->node pointer to srcu_update. Later commits will move additional fields. [ paulmck: Fold in qiang1.zhang@intel.com's memory-leak fix. ] Link: https://lore.kernel.org/all/20230320055751.4120251-1-qiang1.zhang@intel.com/ Suggested-by: Christoph Hellwig Cc: "Rafael J. Wysocki" Cc: "Michał Mirosław" Cc: Dmitry Osipenko Tested-by: Sachin Sant Tested-by: "Zhang, Qiang1" Acked-by: Rafael J. Wysocki Tested-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney

notifier: Add blocking/atomic_notifier_chain_register_unique_prio()

2022-05-19T17:30:30+00:00

Add variant of blocking/atomic_notifier_chain_register() functions that allow registration of a notifier only if it has unique priority, otherwise -EBUSY error code is returned by the new functions. Reviewed-by: Michał Mirosław Signed-off-by: Dmitry Osipenko Signed-off-by: Rafael J. Wysocki

notifier: Add atomic_notifier_call_chain_is_empty()

2022-05-19T17:25:06+00:00

Add atomic_notifier_call_chain_is_empty() that returns true if given atomic call chain is empty. The first user of this new notifier API function will be the kernel power-off core code that will support power-off call chains. The core code will need to check whether there is a power-off handler registered at all in order to decide whether to halt machine or power it off. Reviewed-by: Michał Mirosław Signed-off-by: Dmitry Osipenko Signed-off-by: Rafael J. Wysocki

notifier: Remove atomic_notifier_call_chain_robust()

2021-08-16T16:55:32+00:00

This now has no more users, remove it. Suggested-by: Sebastian Andrzej Siewior Signed-off-by: Valentin Schneider Acked-by: Sebastian Andrzej Siewior Signed-off-by: Rafael J. Wysocki

notifier: Fix broken error handling pattern

2020-09-01T07:58:03+00:00

The current notifiers have the following error handling pattern all over the place: int err, nr; err = __foo_notifier_call_chain(&chain, val_up, v, -1, &nr); if (err & NOTIFIER_STOP_MASK) __foo_notifier_call_chain(&chain, val_down, v, nr-1, NULL) And aside from the endless repetition thereof, it is broken. Consider blocking notifiers; both calls take and drop the rwsem, this means that the notifier list can change in between the two calls, making @nr meaningless. Fix this by replacing all the __foo_notifier_call_chain() functions with foo_notifier_call_chain_robust() that embeds the above pattern, but ensures it is inside a single lock region. Note: I switched atomic_notifier_call_chain_robust() to use the spinlock, since RCU cannot provide the guarantee required for the recovery. Note: software_resume() error handling was broken afaict. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/20200818135804.325626653@infradead.org

kernel/notifier.c: remove blocking_notifier_chain_cond_register()

2019-12-05T03:44:12+00:00

blocking_notifier_chain_cond_register() does not consider system_booting state, which is the only difference between this function and blocking_notifier_cain_register(). This can be a bug and is a piece of duplicate code. Delete blocking_notifier_chain_cond_register() Link: http://lkml.kernel.org/r/1568861888-34045-4-git-send-email-nixiaoming@huawei.com Signed-off-by: Xiaoming Ni Reviewed-by: Andrew Morton Cc: Alan Stern Cc: Alexey Dobriyan Cc: Andy Lutomirski Cc: Anna Schumaker Cc: Arjan van de Ven Cc: Chuck Lever Cc: David S. Miller Cc: Ingo Molnar Cc: J. Bruce Fields Cc: Jeff Layton Cc: Nadia Derbey Cc: "Paul E. McKenney" Cc: Sam Protsenko Cc: Thomas Gleixner Cc: Trond Myklebust Cc: Vasily Averin Cc: Viresh Kumar Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

include/linux/notifier.h: SRCU: fix ctags

2018-11-03T17:09:37+00:00

ctags indexing ("make tags" command) throws this warning: ctags: Warning: include/linux/notifier.h:125: null expansion of name pattern "\1" This is the result of DEFINE_PER_CPU() macro expansion. Fix that by getting rid of line break. Similar fix was already done in commit 25528213fe9f ("tags: Fix DEFINE_PER_CPU expansions"), but this one probably wasn't noticed. Link: http://lkml.kernel.org/r/20181030202808.28027-1-semen.protsenko@linaro.org Fixes: 9c80172b902d ("kernel/SRCU: provide a static initializer") Signed-off-by: Sam Protsenko Cc: Sebastian Andrzej Siewior Cc: Andy Shevchenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/SRCU: provide a static initializer

2018-05-30T08:11:34+00:00

There are macros for static initializer for the three out of four possible notifier types, that are: ATOMIC_NOTIFIER_HEAD() BLOCKING_NOTIFIER_HEAD() RAW_NOTIFIER_HEAD() This patch provides a static initilizer for the forth type to make it complete. Signed-off-by: Sebastian Andrzej Siewior Tested-by: Paul E. McKenney Reviewed-by: Paul E. McKenney Signed-off-by: Rafael J. Wysocki