From 9a789fcfe8605417f7a1a970355f5efa4fe88c64 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Tue, 19 Jun 2018 09:32:30 -0400 Subject: [PATCH] rseq/cleanup: Do not abort rseq c.s. in child on fork() Considering that we explicitly forbid system calls in rseq critical sections, it is not valid to issue a fork or clone system call within a rseq critical section, so rseq_fork() is not required to restart an active rseq c.s. in the child process. Signed-off-by: Mathieu Desnoyers Cc: Andrew Morton Cc: Andy Lutomirski Cc: Ben Maurer Cc: Boqun Feng Cc: Catalin Marinas Cc: Chris Lameter Cc: Dave Watson Cc: Joel Fernandes Cc: Josh Triplett Cc: Linus Torvalds Cc: Michael Kerrisk Cc: Paul E . McKenney Cc: Paul Turner Cc: Peter Zijlstra Cc: Russell King Cc: Shuah Khan Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-api@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Link: https://lore.kernel.org/lkml/20180619133230.4087-4-mathieu.desnoyers@efficios.com Signed-off-by: Ingo Molnar --- include/linux/sched.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 87bf02d..c188264 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1831,9 +1831,7 @@ static inline void rseq_migrate(struct task_struct *t) /* * If parent process has a registered restartable sequences area, the - * child inherits. Only applies when forking a process, not a thread. In - * case a parent fork() in the middle of a restartable sequence, set the - * resume notifier to force the child to retry. + * child inherits. Only applies when forking a process, not a thread. */ static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags) { @@ -1847,7 +1845,6 @@ static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags) t->rseq_len = current->rseq_len; t->rseq_sig = current->rseq_sig; t->rseq_event_mask = current->rseq_event_mask; - rseq_preempt(t); } } -- 2.7.4