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notifier: Fix broken error handling pattern

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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) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20200818135804.325626653@infradead.org
This commit is contained in:
Peter Zijlstra
2020-08-18 15:57:36 +02:00
committed by Ingo Molnar
parent f75aef392f
commit 70d9329857
9 changed files with 147 additions and 140 deletions
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2
tools/power/pm-graph/sleepgraph.py
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@@ -171,7 +171,7 @@ class SystemValues:
tracefuncs = {
'sys_sync': {},
'ksys_sync': {},
'__pm_notifier_call_chain': {},
'pm_notifier_call_chain_robust': {},
'pm_prepare_console': {},
'pm_notifier_call_chain': {},
'freeze_processes': {},