Re: [patch] exclude sync signals from signalfd sets

From: Oleg Nesterov
Date: Thu Jun 21 2007 - 05:27:24 EST


On 06/20, Linus Torvalds wrote:
>
>
> On Wed, 20 Jun 2007, Davide Libenzi wrote:
> >
> > The following patch excludes synchronous signals from being dequeued
> > by a signalfd.
>
> I really prefer the current code. Listign special cases is just ugly. Just
> make it so that thread-local signals stay thread-local, and it's all good.

OK. How about the patch below then? I think this is what Nicholas suggested.

(Sorry for persistance! I can't explain why I think the current behaviour is
not good. Just a personal feeling).

Oleg.

--- signalfd.c~ 2007-06-21 13:00:21.000000000 +0400
+++ signalfd.c 2007-06-21 13:04:45.000000000 +0400
@@ -208,6 +208,15 @@ static int signalfd_copyinfo(struct sign
return err ? -EFAULT: sizeof(*uinfo);
}

+static int
+__signalfd_dequeue(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
+{
+ if (tsk->tgid == current->tgid)
+ tsk = current;
+
+ return dequeue_signal(tsk, mask, info);
+}
+
static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
int nonblock)
{
@@ -218,7 +227,7 @@ static ssize_t signalfd_dequeue(struct s
if (!signalfd_lock(ctx, &lk))
return 0;

- ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
+ ret = __signalfd_dequeue(lk.tsk, &ctx->sigmask, info);
switch (ret) {
case 0:
if (!nonblock)
@@ -232,7 +241,7 @@ static ssize_t signalfd_dequeue(struct s
add_wait_queue(&ctx->wqh, &wait);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
- ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
+ ret = __signalfd_dequeue(lk.tsk, &ctx->sigmask, info);
signalfd_unlock(&lk);
if (ret != 0)
break;
@@ -330,7 +339,7 @@ asmlinkage long sys_signalfd(int ufd, si

init_waitqueue_head(&ctx->wqh);
ctx->sigmask = sigmask;
- ctx->tsk = current;
+ ctx->tsk = current->group_leader;

sighand = current->sighand;
/*

-
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