On Sat, Jul 01, 2017 at 09:23:03PM +0200, Manfred Spraul wrote: > On 06/30/2017 02:01 AM, Paul E. McKenney wrote: > >There is no agreed-upon definition of spin_unlock_wait()'s semantics, > >and it appears that all callers could do just as well with a lock/unlock > >pair. This commit therefore replaces the spin_unlock_wait() call in > >exit_sem() with spin_lock() followed immediately by spin_unlock(). > >This should be safe from a performance perspective because exit_sem() > >is rarely invoked in production. > > > >Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > >Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > >Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx> > >Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> > >Cc: Will Deacon <will.deacon@xxxxxxx> > >Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > >Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > >Cc: Andrea Parri <parri.andrea@xxxxxxxxx> > >Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > Acked-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Applied, thank you! Thanx, Paul > >--- > > ipc/sem.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > >diff --git a/ipc/sem.c b/ipc/sem.c > >index 947dc2348271..e88d0749a929 100644 > >--- a/ipc/sem.c > >+++ b/ipc/sem.c > >@@ -2096,7 +2096,8 @@ void exit_sem(struct task_struct *tsk) > > * possibility where we exit while freeary() didn't > > * finish unlocking sem_undo_list. > > */ > >- spin_unlock_wait(&ulp->lock); > >+ spin_lock(&ulp->lock); > >+ spin_unlock(&ulp->lock); > > rcu_read_unlock(); > > break; > > } > >
