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| author |   Manfred Spraul <manfred@colorfullife.com> | 2022-12-16 16:04:40 +0100 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2023-02-02 22:50:01 -0800 |
| commit | 88ad32a799ddc92eafd2ae204cb43f04ac20a05c (patch) | |
| tree | a4797d1b353073c535eba0f4c05e1cb758ed7337 /include/linux/percpu_counter.h | |
| parent | lib/percpu_counter: percpu_counter_add_batch() overflow/underflow (diff) | |
| download | wireguard-linux-88ad32a799ddc92eafd2ae204cb43f04ac20a05c.tar.xz wireguard-linux-88ad32a799ddc92eafd2ae204cb43f04ac20a05c.zip | |
include/linux/percpu_counter.h: race in uniprocessor percpu_counter_add()
The percpu interface is supposed to be preempt and irq safe.
But:
The uniprocessor implementation of percpu_counter_add() is not irq safe:
if an interrupt happens during the +=, then the result is undefined.
Therefore: switch from preempt_disable() to local_irq_save().
This prevents interrupts from interrupting the +=, and as a side effect
prevents preemption.
Link: https://lkml.kernel.org/r/20221216150441.200533-2-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: "Sun, Jiebin" <jiebin.sun@intel.com>
Cc: <1vier1@web.de>
Cc: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/percpu_counter.h')
| -rw-r--r-- | include/linux/percpu_counter.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index a3aae8d57a42..521a733e21a9 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -152,9 +152,11 @@ __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch) static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount) { - preempt_disable(); + unsigned long flags; + + local_irq_save(flags); fbc->count += amount; - preempt_enable(); + local_irq_restore(flags); } /* non-SMP percpu_counter_add_local is the same with percpu_counter_add */ |