diff --git a/fs/exec.c b/fs/exec.c
index c21a8cc0627709db512597ff2af82ab7c094e67d..073b0b8c6d055a3fd947f16fbdbe5552a6bc34c8 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -50,7 +50,6 @@
#include <linux/tsacct_kern.h>
#include <linux/cn_proc.h>
#include <linux/audit.h>
-#include <linux/signalfd.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
@@ -784,7 +783,6 @@ static int de_thread(struct task_struct *tsk)
* and we can just re-use it all.
*/
if (atomic_read(&oldsighand->count) <= 1) {
- signalfd_detach(tsk);
exit_itimers(sig);
return 0;
}
@@ -923,7 +921,6 @@ static int de_thread(struct task_struct *tsk)
sig->flags = 0;
no_thread_group:
- signalfd_detach(tsk);
exit_itimers(sig);
if (leader)
release_task(leader);
diff --git a/fs/signalfd.c b/fs/signalfd.c
index a8e293d3003432ff493eff7069f32305fa35006a..aefb0be07942d735de747ad8697834368f8a907a 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -11,8 +11,10 @@
* Now using anonymous inode source.
* Thanks to Oleg Nesterov for useful code review and suggestions.
* More comments and suggestions from Arnd Bergmann.
- * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
+ * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br>
* Retrieve multiple signals with one read() call
+ * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org>
+ * Attach to the sighand only during read() and poll().
*/
#include <linux/file.h>
@@ -27,102 +29,12 @@
#include <linux/signalfd.h>
struct signalfd_ctx {
- struct list_head lnk;
- wait_queue_head_t wqh;
sigset_t sigmask;
- struct task_struct *tsk;
};
-struct signalfd_lockctx {
- struct task_struct *tsk;
- unsigned long flags;
-};
-
-/*
- * Tries to acquire the sighand lock. We do not increment the sighand
- * use count, and we do not even pin the task struct, so we need to
- * do it inside an RCU read lock, and we must be prepared for the
- * ctx->tsk going to NULL (in signalfd_deliver()), and for the sighand
- * being detached. We return 0 if the sighand has been detached, or
- * 1 if we were able to pin the sighand lock.
- */
-static int signalfd_lock(struct signalfd_ctx *ctx, struct signalfd_lockctx *lk)
-{
- struct sighand_struct *sighand = NULL;
-
- rcu_read_lock();
- lk->tsk = rcu_dereference(ctx->tsk);
- if (likely(lk->tsk != NULL))
- sighand = lock_task_sighand(lk->tsk, &lk->flags);
- rcu_read_unlock();
-
- if (!sighand)
- return 0;
-
- if (!ctx->tsk) {
- unlock_task_sighand(lk->tsk, &lk->flags);
- return 0;
- }
-
- if (lk->tsk->tgid == current->tgid)
- lk->tsk = current;
-
- return 1;
-}
-
-static void signalfd_unlock(struct signalfd_lockctx *lk)
-{
- unlock_task_sighand(lk->tsk, &lk->flags);
-}
-
-/*
- * This must be called with the sighand lock held.
- */
-void signalfd_deliver(struct task_struct *tsk, int sig)
-{
- struct sighand_struct *sighand = tsk->sighand;
- struct signalfd_ctx *ctx, *tmp;
-
- BUG_ON(!sig);
- list_for_each_entry_safe(ctx, tmp, &sighand->signalfd_list, lnk) {
- /*
- * We use a negative signal value as a way to broadcast that the
- * sighand has been orphaned, so that we can notify all the
- * listeners about this. Remember the ctx->sigmask is inverted,
- * so if the user is interested in a signal, that corresponding
- * bit will be zero.
- */
- if (sig < 0) {
- if (ctx->tsk == tsk) {
- ctx->tsk = NULL;
- list_del_init(&ctx->lnk);
- wake_up(&ctx->wqh);
- }
- } else {
- if (!sigismember(&ctx->sigmask, sig))
- wake_up(&ctx->wqh);
- }
- }
-}
-
-static void signalfd_cleanup(struct signalfd_ctx *ctx)
-{
- struct signalfd_lockctx lk;
-
- /*
- * This is tricky. If the sighand is gone, we do not need to remove
- * context from the list, the list itself won't be there anymore.
- */
- if (signalfd_lock(ctx, &lk)) {
- list_del(&ctx->lnk);
- signalfd_unlock(&lk);
- }
- kfree(ctx);
-}
-
static int signalfd_release(struct inode *inode, struct file *file)
{
- signalfd_cleanup(file->private_data);
+ kfree(file->private_data);
return 0;
}
@@ -130,23 +42,15 @@ static unsigned int signalfd_poll(struct file *file, poll_table *wait)
{
struct signalfd_ctx *ctx = file->private_data;
unsigned int events = 0;
- struct signalfd_lockctx lk;
- poll_wait(file, &ctx->wqh, wait);
+ poll_wait(file, ¤t->sighand->signalfd_wqh, wait);
- /*
- * Let the caller get a POLLIN in this case, ala socket recv() when
- * the peer disconnects.
- */
- if (signalfd_lock(ctx, &lk)) {
- if ((lk.tsk == current &&
- next_signal(&lk.tsk->pending, &ctx->sigmask) > 0) ||
- next_signal(&lk.tsk->signal->shared_pending,
- &ctx->sigmask) > 0)
- events |= POLLIN;
- signalfd_unlock(&lk);
- } else
+ spin_lock_irq(¤t->sighand->siglock);
+ if (next_signal(¤t->pending, &ctx->sigmask) ||
+ next_signal(¤t->signal->shared_pending,
+ &ctx->sigmask))
events |= POLLIN;
+ spin_unlock_irq(¤t->sighand->siglock);
return events;
}
@@ -219,59 +123,46 @@ static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
int nonblock)
{
ssize_t ret;
- struct signalfd_lockctx lk;
DECLARE_WAITQUEUE(wait, current);
- if (!signalfd_lock(ctx, &lk))
- return 0;
-
- ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
+ spin_lock_irq(¤t->sighand->siglock);
+ ret = dequeue_signal(current, &ctx->sigmask, info);
switch (ret) {
case 0:
if (!nonblock)
break;
ret = -EAGAIN;
default:
- signalfd_unlock(&lk);
+ spin_unlock_irq(¤t->sighand->siglock);
return ret;
}
- add_wait_queue(&ctx->wqh, &wait);
+ add_wait_queue(¤t->sighand->signalfd_wqh, &wait);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
- ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
- signalfd_unlock(&lk);
+ ret = dequeue_signal(current, &ctx->sigmask, info);
if (ret != 0)
break;
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
+ spin_unlock_irq(¤t->sighand->siglock);
schedule();
- ret = signalfd_lock(ctx, &lk);
- if (unlikely(!ret)) {
- /*
- * Let the caller read zero byte, ala socket
- * recv() when the peer disconnect. This test
- * must be done before doing a dequeue_signal(),
- * because if the sighand has been orphaned,
- * the dequeue_signal() call is going to crash
- * because ->sighand will be long gone.
- */
- break;
- }
+ spin_lock_irq(¤t->sighand->siglock);
}
+ spin_unlock_irq(¤t->sighand->siglock);
- remove_wait_queue(&ctx->wqh, &wait);
+ remove_wait_queue(¤t->sighand->signalfd_wqh, &wait);
__set_current_state(TASK_RUNNING);
return ret;
}
/*
- * Returns either the size of a "struct signalfd_siginfo", or zero if the
- * sighand we are attached to, has been orphaned. The "count" parameter
- * must be at least the size of a "struct signalfd_siginfo".
+ * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative
+ * error code. The "count" parameter must be at least the size of a
+ * "struct signalfd_siginfo".
*/
static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
loff_t *ppos)
@@ -287,7 +178,6 @@ static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
return -EINVAL;
siginfo = (struct signalfd_siginfo __user *) buf;
-
do {
ret = signalfd_dequeue(ctx, &info, nonblock);
if (unlikely(ret <= 0))
@@ -300,7 +190,7 @@ static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
nonblock = 1;
} while (--count);
- return total ? total : ret;
+ return total ? total: ret;
}
static const struct file_operations signalfd_fops = {
@@ -309,20 +199,13 @@ static const struct file_operations signalfd_fops = {
.read = signalfd_read,
};
-/*
- * Create a file descriptor that is associated with our signal
- * state. We can pass it around to others if we want to, but
- * it will always be _our_ signal state.
- */
asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask)
{
int error;
sigset_t sigmask;
struct signalfd_ctx *ctx;
- struct sighand_struct *sighand;
struct file *file;
struct inode *inode;
- struct signalfd_lockctx lk;
if (sizemask != sizeof(sigset_t) ||
copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
@@ -335,17 +218,7 @@ asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemas
if (!ctx)
return -ENOMEM;
- init_waitqueue_head(&ctx->wqh);
ctx->sigmask = sigmask;
- ctx->tsk = current->group_leader;
-
- sighand = current->sighand;
- /*
- * Add this fd to the list of signal listeners.
- */
- spin_lock_irq(&sighand->siglock);
- list_add_tail(&ctx->lnk, &sighand->signalfd_list);
- spin_unlock_irq(&sighand->siglock);
/*
* When we call this, the initialization must be complete, since
@@ -364,23 +237,18 @@ asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemas
fput(file);
return -EINVAL;
}
- /*
- * We need to be prepared of the fact that the sighand this fd
- * is attached to, has been detched. In that case signalfd_lock()
- * will return 0, and we'll just skip setting the new mask.
- */
- if (signalfd_lock(ctx, &lk)) {
- ctx->sigmask = sigmask;
- signalfd_unlock(&lk);
- }
- wake_up(&ctx->wqh);
+ spin_lock_irq(¤t->sighand->siglock);
+ ctx->sigmask = sigmask;
+ spin_unlock_irq(¤t->sighand->siglock);
+
+ wake_up(¤t->sighand->signalfd_wqh);
fput(file);
}
return ufd;
err_fdalloc:
- signalfd_cleanup(ctx);
+ kfree(ctx);
return error;
}
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index cab741c2d6033ad937b761852def3fbbf60b763b..f8abfa349ef924344a11b1fd9739e68bd4d72b24 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -86,7 +86,7 @@ extern struct nsproxy init_nsproxy;
.count = ATOMIC_INIT(1), \
.action = { { { .sa_handler = NULL, } }, }, \
.siglock = __SPIN_LOCK_UNLOCKED(sighand.siglock), \
- .signalfd_list = LIST_HEAD_INIT(sighand.signalfd_list), \
+ .signalfd_wqh = __WAIT_QUEUE_HEAD_INITIALIZER(sighand.signalfd_wqh), \
}
extern struct group_info init_groups;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3de79016f2a669dbbb5bd16395d3458032be2b86..a01ac6dd5f5e1c07d9a54a8f879512db2eac3905 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -438,7 +438,7 @@ struct sighand_struct {
atomic_t count;
struct k_sigaction action[_NSIG];
spinlock_t siglock;
- struct list_head signalfd_list;
+ wait_queue_head_t signalfd_wqh;
};
struct pacct_struct {
diff --git a/include/linux/signalfd.h b/include/linux/signalfd.h
index 5104294956906c038e4359ab4e37c35632e2e478..4c9ff0910ae01d39f691a23c9acf5d1db48b06d2 100644
--- a/include/linux/signalfd.h
+++ b/include/linux/signalfd.h
@@ -45,49 +45,17 @@ struct signalfd_siginfo {
#ifdef CONFIG_SIGNALFD
/*
- * Deliver the signal to listening signalfd. This must be called
- * with the sighand lock held. Same are the following that end up
- * calling signalfd_deliver().
- */
-void signalfd_deliver(struct task_struct *tsk, int sig);
-
-/*
- * No need to fall inside signalfd_deliver() if no signal listeners
- * are available.
+ * Deliver the signal to listening signalfd.
*/
static inline void signalfd_notify(struct task_struct *tsk, int sig)
{
- if (unlikely(!list_empty(&tsk->sighand->signalfd_list)))
- signalfd_deliver(tsk, sig);
-}
-
-/*
- * The signal -1 is used to notify the signalfd that the sighand
- * is on its way to be detached.
- */
-static inline void signalfd_detach_locked(struct task_struct *tsk)
-{
- if (unlikely(!list_empty(&tsk->sighand->signalfd_list)))
- signalfd_deliver(tsk, -1);
-}
-
-static inline void signalfd_detach(struct task_struct *tsk)
-{
- struct sighand_struct *sighand = tsk->sighand;
-
- if (unlikely(!list_empty(&sighand->signalfd_list))) {
- spin_lock_irq(&sighand->siglock);
- signalfd_deliver(tsk, -1);
- spin_unlock_irq(&sighand->siglock);
- }
+ if (unlikely(waitqueue_active(&tsk->sighand->signalfd_wqh)))
+ wake_up(&tsk->sighand->signalfd_wqh);
}
#else /* CONFIG_SIGNALFD */
-#define signalfd_deliver(t, s) do { } while (0)
-#define signalfd_notify(t, s) do { } while (0)
-#define signalfd_detach_locked(t) do { } while (0)
-#define signalfd_detach(t) do { } while (0)
+static inline void signalfd_notify(struct task_struct *tsk, int sig) { }
#endif /* CONFIG_SIGNALFD */
diff --git a/kernel/exit.c b/kernel/exit.c
index 06b24b3aa370c69577012023b12573d4c7624d19..993369ee94d1ebb8d4c7675a821e90abf8a1737e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -24,7 +24,6 @@
#include <linux/pid_namespace.h>
#include <linux/ptrace.h>
#include <linux/profile.h>
-#include <linux/signalfd.h>
#include <linux/mount.h>
#include <linux/proc_fs.h>
#include <linux/kthread.h>
@@ -86,14 +85,6 @@ static void __exit_signal(struct task_struct *tsk)
sighand = rcu_dereference(tsk->sighand);
spin_lock(&sighand->siglock);
- /*
- * Notify that this sighand has been detached. This must
- * be called with the tsk->sighand lock held. Also, this
- * access tsk->sighand internally, so it must be called
- * before tsk->sighand is reset.
- */
- signalfd_detach_locked(tsk);
-
posix_cpu_timers_exit(tsk);
if (atomic_dec_and_test(&sig->count))
posix_cpu_timers_exit_group(tsk);
diff --git a/kernel/fork.c b/kernel/fork.c
index 7332e236d3676153dc9f40c1a78848e6e2810632..33f12f48684a0053a82d72506c1d7ec1e7ca6a15 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1438,7 +1438,7 @@ static void sighand_ctor(void *data, struct kmem_cache *cachep,
struct sighand_struct *sighand = data;
spin_lock_init(&sighand->siglock);
- INIT_LIST_HEAD(&sighand->signalfd_list);
+ init_waitqueue_head(&sighand->signalfd_wqh);
}
void __init proc_caches_init(void)
diff --git a/kernel/signal.c b/kernel/signal.c
index 3169bed0b4d0e44166b37c48ed663d516a9ccba5..9fb91a32eddaddfd47d09cb0aa66586a5635a39e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -378,8 +378,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
/* We only dequeue private signals from ourselves, we don't let
* signalfd steal them
*/
- if (likely(tsk == current))
- signr = __dequeue_signal(&tsk->pending, mask, info);
+ signr = __dequeue_signal(&tsk->pending, mask, info);
if (!signr) {
signr = __dequeue_signal(&tsk->signal->shared_pending,
mask, info);
@@ -407,8 +406,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
}
}
}
- if (likely(tsk == current))
- recalc_sigpending();
+ recalc_sigpending();
if (signr && unlikely(sig_kernel_stop(signr))) {
/*
* Set a marker that we have dequeued a stop signal. Our
@@ -425,7 +423,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
}
- if (signr && likely(tsk == current) &&
+ if (signr &&
((info->si_code & __SI_MASK) == __SI_TIMER) &&
info->si_sys_private){
/*