On Wed, Jun 13, 2018 at 10:34 PM, Leon Romanovsky <l...@kernel.org> wrote: > > Hi Cong, > > If the compiler optimizes the first line (mutex_lock) as you wrote, > it will reuse "f" for the second line (mutex_unlock) too.
Nope, check the assembly if you don't trust me, at least my compiler always fetches ctx->file without this patch. I can show you the assembly code tomorrow (too late to access my dev machine now). > > You need to ensure that ucma_modify_id() doesn't run in parallel to > anything that uses "ctx->file" directly and indirectly. > Talk is easy, show me the code. :) I knew there is probably some other race with this code even after my patch, possibly with ->close() for example, but for this specific unlock warning, this patch is sufficient. I can't solve all the races in one patch.
