From: Oleg Nesterov do_sigaction() does not need tasklist_lock anymore, we can simplify the code. Signed-off-by: Oleg Nesterov Signed-off-by: Andrew Morton --- kernel/signal.c | 22 +++------------------- 1 files changed, 3 insertions(+), 19 deletions(-) diff -puN kernel/signal.c~do_sigaction-dont-take-tasklist_lock kernel/signal.c --- 25/kernel/signal.c~do_sigaction-dont-take-tasklist_lock Wed Feb 22 16:51:04 2006 +++ 25-akpm/kernel/signal.c Wed Feb 22 16:51:04 2006 @@ -2301,8 +2301,7 @@ sys_rt_sigqueueinfo(int pid, int sig, si return kill_proc_info(sig, &info, pid); } -int -do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) +int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) { struct k_sigaction *k; sigset_t mask; @@ -2328,6 +2327,7 @@ do_sigaction(int sig, struct k_sigaction if (act) { sigdelsetmask(&act->sa.sa_mask, sigmask(SIGKILL) | sigmask(SIGSTOP)); + *k = *act; /* * POSIX 3.3.1.3: * "Setting a signal action to SIG_IGN for a signal that is @@ -2340,19 +2340,8 @@ do_sigaction(int sig, struct k_sigaction * be discarded, whether or not it is blocked" */ if (act->sa.sa_handler == SIG_IGN || - (act->sa.sa_handler == SIG_DFL && - sig_kernel_ignore(sig))) { - /* - * This is a fairly rare case, so we only take the - * tasklist_lock once we're sure we'll need it. - * Now we must do this little unlock and relock - * dance to maintain the lock hierarchy. - */ + (act->sa.sa_handler == SIG_DFL && sig_kernel_ignore(sig))) { struct task_struct *t = current; - spin_unlock_irq(&t->sighand->siglock); - read_lock(&tasklist_lock); - spin_lock_irq(&t->sighand->siglock); - *k = *act; sigemptyset(&mask); sigaddset(&mask, sig); rm_from_queue_full(&mask, &t->signal->shared_pending); @@ -2361,12 +2350,7 @@ do_sigaction(int sig, struct k_sigaction recalc_sigpending_tsk(t); t = next_thread(t); } while (t != current); - spin_unlock_irq(¤t->sighand->siglock); - read_unlock(&tasklist_lock); - return 0; } - - *k = *act; } spin_unlock_irq(¤t->sighand->siglock); _