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authorOleg Nesterov <oleg@redhat.com>2011-04-27 13:54:20 -0400
committerOleg Nesterov <oleg@redhat.com>2011-04-28 07:01:36 -0400
commit73ef4aeb61b53fce464a7e24ef03a26f98b2f617 (patch)
tree15acc5d7ded643ccd1da1d502033822a2452497c
parentfec9993db093acfc3999a364e31f8adae41fcb28 (diff)
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 <oleg@redhat.com> Reviewed-by: Matt Fleming <matt.fleming@linux.intel.com> Acked-by: Tejun Heo <tj@kernel.org>
-rw-r--r--kernel/signal.c29
1 files 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
@@ -2300,12 +2300,6 @@ long do_no_restart_syscall(struct restart_block *param)
2300} 2300}
2301 2301
2302/* 2302/*
2303 * We don't need to get the kernel lock - this is all local to this
2304 * particular thread.. (and that's good, because this is _heavily_
2305 * used by various programs)
2306 */
2307
2308/*
2309 * This is also useful for kernel threads that want to temporarily 2303 * This is also useful for kernel threads that want to temporarily
2310 * (or permanently) block certain signals. 2304 * (or permanently) block certain signals.
2311 * 2305 *
@@ -2315,30 +2309,33 @@ long do_no_restart_syscall(struct restart_block *param)
2315 */ 2309 */
2316int sigprocmask(int how, sigset_t *set, sigset_t *oldset) 2310int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2317{ 2311{
2318 int error; 2312 struct task_struct *tsk = current;
2313 sigset_t newset;
2319 2314
2320 spin_lock_irq(&current->sighand->siglock); 2315 /* Lockless, only current can change ->blocked, never from irq */
2321 if (oldset) 2316 if (oldset)
2322 *oldset = current->blocked; 2317 *oldset = tsk->blocked;
2323 2318
2324 error = 0;
2325 switch (how) { 2319 switch (how) {
2326 case SIG_BLOCK: 2320 case SIG_BLOCK:
2327 sigorsets(&current->blocked, &current->blocked, set); 2321 sigorsets(&newset, &tsk->blocked, set);
2328 break; 2322 break;
2329 case SIG_UNBLOCK: 2323 case SIG_UNBLOCK:
2330 signandsets(&current->blocked, &current->blocked, set); 2324 signandsets(&newset, &tsk->blocked, set);
2331 break; 2325 break;
2332 case SIG_SETMASK: 2326 case SIG_SETMASK:
2333 current->blocked = *set; 2327 newset = *set;
2334 break; 2328 break;
2335 default: 2329 default:
2336 error = -EINVAL; 2330 return -EINVAL;
2337 } 2331 }
2332
2333 spin_lock_irq(&tsk->sighand->siglock);
2334 tsk->blocked = newset;
2338 recalc_sigpending(); 2335 recalc_sigpending();
2339 spin_unlock_irq(&current->sighand->siglock); 2336 spin_unlock_irq(&tsk->sighand->siglock);
2340 2337
2341 return error; 2338 return 0;
2342} 2339}
2343 2340
2344/** 2341/**