Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6

[linux.git] / fs / signalfd.c

diff --git a/fs/signalfd.c b/fs/signalfd.c
index a8e293d3003432ff493eff7069f32305fa35006a..fb7f7e8034df512db10978276d7c2cf8f9cc0a75 100644 (file)
--- 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.
  *      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 <[email protected]>
+ *  Sat May 19, 2007: Davi E. M. Arnaut <[email protected]>

  *      Retrieve multiple signals with one read() call
  *      Retrieve multiple signals with one read() call

+ *  Sun Jul 15, 2007: Davide Libenzi <[email protected]>
+ *      Attach to the sighand only during read() and poll().

  */
 
 #include <linux/file.h>
  */
 
 #include <linux/file.h>


@@ -27,102 +29,12 @@
 #include <linux/signalfd.h>
 
 struct signalfd_ctx {
 #include <linux/signalfd.h>
 
 struct signalfd_ctx {

-       struct list_head lnk;
-       wait_queue_head_t wqh;

        sigset_t sigmask;
        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)
 {
 static int signalfd_release(struct inode *inode, struct file *file)
 {

-       signalfd_cleanup(file->private_data);
+       kfree(file->private_data);

        return 0;
 }
 
        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_ctx *ctx = file->private_data;
        unsigned int events = 0;

-       struct signalfd_lockctx lk;

 
 

-       poll_wait(file, &ctx->wqh, wait);
+       poll_wait(file, &current->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(&current->sighand->siglock);
+       if (next_signal(&current->pending, &ctx->sigmask) ||
+           next_signal(&current->signal->shared_pending,
+                       &ctx->sigmask))

                events |= POLLIN;
                events |= POLLIN;

+       spin_unlock_irq(&current->sighand->siglock);

 
        return events;
 }
 
        return events;
 }


@@ -170,45 +74,45 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
         * If you change siginfo_t structure, please be sure
         * this code is fixed accordingly.
         */
         * If you change siginfo_t structure, please be sure
         * this code is fixed accordingly.
         */

-       err |= __put_user(kinfo->si_signo, &uinfo->signo);
-       err |= __put_user(kinfo->si_errno, &uinfo->err);
-       err |= __put_user((short)kinfo->si_code, &uinfo->code);
+       err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo);
+       err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno);
+       err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code);

        switch (kinfo->si_code & __SI_MASK) {
        case __SI_KILL:
        switch (kinfo->si_code & __SI_MASK) {
        case __SI_KILL:

-               err |= __put_user(kinfo->si_pid, &uinfo->pid);
-               err |= __put_user(kinfo->si_uid, &uinfo->uid);
+               err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
+               err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);

                break;
        case __SI_TIMER:
                break;
        case __SI_TIMER:

-                err |= __put_user(kinfo->si_tid, &uinfo->tid);
-                err |= __put_user(kinfo->si_overrun, &uinfo->overrun);
-                err |= __put_user((long)kinfo->si_ptr, &uinfo->svptr);
+                err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid);
+                err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun);
+                err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);

                break;
        case __SI_POLL:
                break;
        case __SI_POLL:

-               err |= __put_user(kinfo->si_band, &uinfo->band);
-               err |= __put_user(kinfo->si_fd, &uinfo->fd);
+               err |= __put_user(kinfo->si_band, &uinfo->ssi_band);
+               err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd);

                break;
        case __SI_FAULT:
                break;
        case __SI_FAULT:

-               err |= __put_user((long)kinfo->si_addr, &uinfo->addr);
+               err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr);

 #ifdef __ARCH_SI_TRAPNO
 #ifdef __ARCH_SI_TRAPNO

-               err |= __put_user(kinfo->si_trapno, &uinfo->trapno);
+               err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno);

 #endif
                break;
        case __SI_CHLD:
 #endif
                break;
        case __SI_CHLD:

-               err |= __put_user(kinfo->si_pid, &uinfo->pid);
-               err |= __put_user(kinfo->si_uid, &uinfo->uid);
-               err |= __put_user(kinfo->si_status, &uinfo->status);
-               err |= __put_user(kinfo->si_utime, &uinfo->utime);
-               err |= __put_user(kinfo->si_stime, &uinfo->stime);
+               err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
+               err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
+               err |= __put_user(kinfo->si_status, &uinfo->ssi_status);
+               err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime);
+               err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime);

                break;
        case __SI_RT: /* This is not generated by the kernel as of now. */
        case __SI_MESGQ: /* But this is */
                break;
        case __SI_RT: /* This is not generated by the kernel as of now. */
        case __SI_MESGQ: /* But this is */

-               err |= __put_user(kinfo->si_pid, &uinfo->pid);
-               err |= __put_user(kinfo->si_uid, &uinfo->uid);
-               err |= __put_user((long)kinfo->si_ptr, &uinfo->svptr);
+               err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
+               err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);
+               err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr);

                break;
        default: /* this is just in case for now ... */
                break;
        default: /* this is just in case for now ... */

-               err |= __put_user(kinfo->si_pid, &uinfo->pid);
-               err |= __put_user(kinfo->si_uid, &uinfo->uid);
+               err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid);
+               err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid);

                break;
        }
 
                break;
        }
 


@@ -219,59 +123,46 @@ static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info,
                                int nonblock)
 {
        ssize_t ret;
                                int nonblock)
 {
        ssize_t ret;

-       struct signalfd_lockctx lk;

        DECLARE_WAITQUEUE(wait, current);
 
        DECLARE_WAITQUEUE(wait, current);
 

-       if (!signalfd_lock(ctx, &lk))
-               return 0;
-
-       ret = dequeue_signal(lk.tsk, &ctx->sigmask, info);
+       spin_lock_irq(&current->sighand->siglock);
+       ret = dequeue_signal(current, &ctx->sigmask, info);

        switch (ret) {
        case 0:
                if (!nonblock)
                        break;
                ret = -EAGAIN;
        default:
        switch (ret) {
        case 0:
                if (!nonblock)
                        break;
                ret = -EAGAIN;
        default:

-               signalfd_unlock(&lk);
+               spin_unlock_irq(&current->sighand->siglock);

                return ret;
        }
 
                return ret;
        }
 

-       add_wait_queue(&ctx->wqh, &wait);
+       add_wait_queue(&current->sighand->signalfd_wqh, &wait);

        for (;;) {
                set_current_state(TASK_INTERRUPTIBLE);
        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;
                }
                if (ret != 0)
                        break;
                if (signal_pending(current)) {
                        ret = -ERESTARTSYS;
                        break;
                }

+               spin_unlock_irq(&current->sighand->siglock);

                schedule();
                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(&current->sighand->siglock);

        }
        }

+       spin_unlock_irq(&current->sighand->siglock);

 
 

-       remove_wait_queue(&ctx->wqh, &wait);
+       remove_wait_queue(&current->sighand->signalfd_wqh, &wait);

        __set_current_state(TASK_RUNNING);
 
        return ret;
 }
 
 /*
        __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)
  */
 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;
                return -EINVAL;
 
        siginfo = (struct signalfd_siginfo __user *) buf;

-

        do {
                ret = signalfd_dequeue(ctx, &info, nonblock);
                if (unlikely(ret <= 0))
        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);
 
                nonblock = 1;
        } while (--count);
 

-       return total ? total : ret;
+       return total ? total: ret;

 }
 
 static const struct file_operations signalfd_fops = {
 }
 
 static const struct file_operations signalfd_fops = {


@@ -309,20 +199,13 @@ static const struct file_operations signalfd_fops = {
        .read           = signalfd_read,
 };
 
        .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;
 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 file *file;
        struct inode *inode;

-       struct signalfd_lockctx lk;

 
        if (sizemask != sizeof(sigset_t) ||
            copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
 
        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;
 
                if (!ctx)
                        return -ENOMEM;
 

-               init_waitqueue_head(&ctx->wqh);

                ctx->sigmask = sigmask;
                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
 
                /*
                 * 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;
                }
                        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(&current->sighand->siglock);
+               ctx->sigmask = sigmask;
+               spin_unlock_irq(&current->sighand->siglock);
+
+               wake_up(&current->sighand->signalfd_wqh);

                fput(file);
        }
 
        return ufd;
 
 err_fdalloc:
                fput(file);
        }
 
        return ufd;
 
 err_fdalloc:

-       signalfd_cleanup(ctx);
+       kfree(ctx);

        return error;
 }
 
        return error;
 }