From 73ef4aeb61b53fce464a7e24ef03a26f98b2f617 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 27 Apr 2011 19:54:20 +0200 Subject: [PATCH] signal: sigprocmask: narrow the scope of ->siglock No functional changes, preparation to simplify the review of the next change. 1. We can read current->block lockless, nobody else can ever change this mask. 2. Calculate the resulting sigset_t outside of ->siglock into the temporary variable, then take ->siglock and change ->blocked. Also, kill the stale comment about BKL. Signed-off-by: Oleg Nesterov Reviewed-by: Matt Fleming Acked-by: Tejun Heo --- kernel/signal.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 707736e64e0e..e8308e3238c1 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2299,12 +2299,6 @@ long do_no_restart_syscall(struct restart_block *param) return -EINTR; } -/* - * We don't need to get the kernel lock - this is all local to this - * particular thread.. (and that's good, because this is _heavily_ - * used by various programs) - */ - /* * This is also useful for kernel threads that want to temporarily * (or permanently) block certain signals. @@ -2315,30 +2309,33 @@ long do_no_restart_syscall(struct restart_block *param) */ int sigprocmask(int how, sigset_t *set, sigset_t *oldset) { - int error; + struct task_struct *tsk = current; + sigset_t newset; - spin_lock_irq(¤t->sighand->siglock); + /* Lockless, only current can change ->blocked, never from irq */ if (oldset) - *oldset = current->blocked; + *oldset = tsk->blocked; - error = 0; switch (how) { case SIG_BLOCK: - sigorsets(¤t->blocked, ¤t->blocked, set); + sigorsets(&newset, &tsk->blocked, set); break; case SIG_UNBLOCK: - signandsets(¤t->blocked, ¤t->blocked, set); + signandsets(&newset, &tsk->blocked, set); break; case SIG_SETMASK: - current->blocked = *set; + newset = *set; break; default: - error = -EINVAL; + return -EINVAL; } + + spin_lock_irq(&tsk->sighand->siglock); + tsk->blocked = newset; recalc_sigpending(); - spin_unlock_irq(¤t->sighand->siglock); + spin_unlock_irq(&tsk->sighand->siglock); - return error; + return 0; } /** -- 2.20.1