On Sat, Oct 08, 2022, Hao Peng wrote: > From: Peng Hao <flyingpeng@xxxxxxxxxxx> > > Synchronization operations on the writer side of SRCU should be > invoked within the mutex. Why? Synchronizing SRCU is necessary only to ensure that all previous readers go away before the old filter is freed. There's no need to serialize synchronization between writers. The mutex ensures each writer operates on the "new" filter that's set by the previous writer, i.e. there's no danger of a double-free. And the next writer will wait for readers to _its_ "new" filter. I think it's a moot point though, as this is a subset of patch I posted[*] to fix other issues with the PMU event filter. [*] https://lore.kernel.org/all/20220923001355.3741194-2-seanjc@xxxxxxxxxx
