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* [patch 2/13] signal/timer/event fds v9 - signalfd core ...
@ 2007-03-31 20:27 Davide Libenzi
  2007-03-31 21:07 ` Davide Libenzi
  0 siblings, 1 reply; 2+ messages in thread
From: Davide Libenzi @ 2007-03-31 20:27 UTC (permalink / raw)
  To: Linux Kernel Mailing List
  Cc: Andrew Morton, Linus Torvalds, Oleg Nesterov, Eric W. Biederman


This patch series implements the new signalfd() system call.
I took part of the original Linus code (and you know how
badly it can be broken :), and I added even more breakage ;)
Signals are fetched from the same signal queue used by the process,
so signalfd will compete with standard kernel delivery in dequeue_signal().
If you want to reliably fetch signals on the signalfd file, you need to
block them with sigprocmask(SIG_BLOCK).
This seems to be working fine on my Dual Opteron machine. I made a quick 
test program for it:

http://www.xmailserver.org/signafd-test.c

The signalfd() system call implements signal delivery into a file 
descriptor receiver. The signalfd file descriptor if created with the 
following API:

int signalfd(int ufd, const sigset_t *mask, size_t masksize);

The "ufd" parameter allows to change an existing signalfd sigmask, w/out 
going to close/create cycle (Linus idea). Use "ufd" == -1 if you want a 
brand new signalfd file.
The "mask" allows to specify the signal mask of signals that we are 
interested in. The "masksize" parameter is the size of "mask".
The signalfd fd supports the poll(2) and read(2) system calls. The poll(2)
will return POLLIN when signals are available to be dequeued. As a direct
consequence of supporting the Linux poll subsystem, the signalfd fd can use
used together with epoll(2) too.
The read(2) system call will return a "struct signalfd_siginfo" structure
in the userspace supplied buffer. The return value is the number of bytes
copied in the supplied buffer, or -1 in case of error. The read(2) call
can also return 0, in case the sighand structure to which the signalfd
was attached, has been orphaned. The O_NONBLOCK flag is also supported, and
read(2) will return -EAGAIN in case no signal is available.
If the size of the buffer passed to read(2) is lower than
sizeof(struct signalfd_siginfo), -EINVAL is returned. A read from the
signalfd can also return -ERESTARTSYS in case a signal hits the process.
The format of the struct signalfd_siginfo is, and the valid fields depends
of the (->code & __SI_MASK) value, in the same way a struct siginfo would:

struct signalfd_siginfo {
	__u32 signo;	/* si_signo */
	__s32 err;	/* si_errno */
	__s32 code;	/* si_code */
	__u32 pid;	/* si_pid */
	__u32 uid;	/* si_uid */
	__s32 fd;	/* si_fd */
	__u32 tid;	/* si_fd */
	__u32 band;	/* si_band */
	__u32 overrun;	/* si_overrun */
	__u32 trapno;	/* si_trapno */
	__s32 status;	/* si_status */
	__s32 svint;	/* si_int */
	__u64 svptr;	/* si_ptr */
	__u64 utime;	/* si_utime */
	__u64 stime;	/* si_stime */
	__u64 addr;	/* si_addr */
};



Signed-off-by: Davide Libenzi <davidel@xmailserver.org>



- Davide



Index: linux-2.6.21-rc5.fds/fs/signalfd.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.21-rc5.fds/fs/signalfd.c	2007-03-31 12:29:28.000000000 -0700
@@ -0,0 +1,357 @@
+/*
+ *  fs/signalfd.c
+ *
+ *  Copyright (C) 2003  Linus Torvalds
+ *
+ *  Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org>
+ *      Changed ->read() to return a siginfo strcture instead of signal number.
+ *      Fixed locking in ->poll().
+ *      Added sighand-detach notification.
+ *      Added fd re-use in sys_signalfd() syscall.
+ *      Now using anonymous inode source.
+ *      Thanks to Oleg Nesterov for useful code review and suggestions.
+ *      More comments and suggestions from Arnd Bergmann.
+ */
+
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/list.h>
+#include <linux/anon_inodes.h>
+#include <linux/signalfd.h>
+
+#include <asm/uaccess.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 && !ctx->tsk) {
+		unlock_task_sighand(lk->tsk, &lk->flags);
+		sighand = NULL;
+	}
+
+	return sighand != NULL;
+}
+
+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);
+	return 0;
+}
+
+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);
+
+	/*
+	 * Let the caller get a POLLIN in this case, ala socket recv() when
+	 * the peer disconnects.
+	 */
+	if (signalfd_lock(ctx, &lk)) {
+		if (next_signal(&lk.tsk->pending, &ctx->sigmask) > 0 ||
+		    next_signal(&lk.tsk->signal->shared_pending,
+				&ctx->sigmask) > 0)
+			events |= POLLIN;
+		signalfd_unlock(&lk);
+	} else
+		events |= POLLIN;
+
+	return events;
+}
+
+/*
+ * Copied from copy_siginfo_to_user() in kernel/signal.c
+ */
+static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
+			     siginfo_t const *kinfo)
+{
+	long err;
+
+	BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128);
+
+	/*
+	 * Unused memebers should be zero ...
+	 */
+	err = __clear_user(uinfo, sizeof(*uinfo));
+
+	/*
+	 * 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);
+	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);
+		break;
+	case __SI_TIMER:
+		 err |= __put_user(kinfo->si_tid, &uinfo->tid);
+		 err |= __put_user(kinfo->si_overrun, &uinfo->overrun);
+		 err |= __put_user(kinfo->si_ptr, &uinfo->svptr);
+		break;
+	case __SI_POLL:
+		err |= __put_user(kinfo->si_band, &uinfo->band);
+		err |= __put_user(kinfo->si_fd, &uinfo->fd);
+		break;
+	case __SI_FAULT:
+		err |= __put_user(kinfo->si_addr, &uinfo->addr);
+#ifdef __ARCH_SI_TRAPNO
+		err |= __put_user(kinfo->si_trapno, &uinfo->trapno);
+#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);
+		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(kinfo->si_ptr, &uinfo->svptr);
+		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);
+		break;
+	}
+
+	return err ? -EFAULT: sizeof(*uinfo);
+}
+
+/*
+ * 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".
+ */
+static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count,
+			     loff_t *ppos)
+{
+	struct signalfd_ctx *ctx = file->private_data;
+	ssize_t res = 0;
+	int locked, signo;
+	siginfo_t info;
+	struct signalfd_lockctx lk;
+	DECLARE_WAITQUEUE(wait, current);
+
+	if (count < sizeof(struct signalfd_siginfo))
+		return -EINVAL;
+	locked = signalfd_lock(ctx, &lk);
+	if (!locked)
+		return 0;
+	res = -EAGAIN;
+	signo = dequeue_signal(lk.tsk, &ctx->sigmask, &info);
+	if (signo == 0 && !(file->f_flags & O_NONBLOCK)) {
+		add_wait_queue(&ctx->wqh, &wait);
+		for (;;) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			signo = dequeue_signal(lk.tsk, &ctx->sigmask, &info);
+			if (signo != 0)
+				break;
+			if (signal_pending(current)) {
+				res = -ERESTARTSYS;
+				break;
+			}
+			signalfd_unlock(&lk);
+			schedule();
+			locked = signalfd_lock(ctx, &lk);
+			if (unlikely(!locked)) {
+				/*
+				 * 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.
+				 */
+				res = 0;
+				break;
+			}
+		}
+		remove_wait_queue(&ctx->wqh, &wait);
+		__set_current_state(TASK_RUNNING);
+	}
+	if (likely(locked))
+		signalfd_unlock(&lk);
+	if (likely(signo))
+		res = signalfd_copyinfo((struct signalfd_siginfo __user *) buf,
+					&info);
+
+	return res;
+}
+
+
+static const struct file_operations signalfd_fops = {
+	.release	= signalfd_release,
+	.poll		= signalfd_poll,
+	.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)))
+		return error = -EINVAL;
+	sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+	signotset(&sigmask);
+
+	if (ufd == -1) {
+		ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
+		if (!ctx)
+			return -ENOMEM;
+
+		init_waitqueue_head(&ctx->wqh);
+		ctx->sigmask = sigmask;
+		ctx->tsk = current;
+
+		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
+		 * aino_getfd() will install the fd.
+		 */
+		error = aino_getfd(&ufd, &inode, &file, "[signalfd]",
+				   &signalfd_fops, ctx);
+		if (error)
+			goto err_fdalloc;
+	} else {
+		file = fget(ufd);
+		if (!file)
+			return -EBADF;
+		ctx = file->private_data;
+		if (file->f_op != &signalfd_fops) {
+			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);
+		fput(file);
+	}
+
+	return ufd;
+
+err_fdalloc:
+	signalfd_cleanup(ctx);
+	return error;
+}
+
Index: linux-2.6.21-rc5.fds/include/linux/init_task.h
===================================================================
--- linux-2.6.21-rc5.fds.orig/include/linux/init_task.h	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/include/linux/init_task.h	2007-03-31 12:29:28.000000000 -0700
@@ -84,6 +84,7 @@
 	.count		= ATOMIC_INIT(1), 				\
 	.action		= { { { .sa_handler = NULL, } }, },		\
 	.siglock	= __SPIN_LOCK_UNLOCKED(sighand.siglock),	\
+	.signalfd_list	= LIST_HEAD_INIT(sighand.signalfd_list),	\
 }
 
 extern struct group_info init_groups;
Index: linux-2.6.21-rc5.fds/include/linux/sched.h
===================================================================
--- linux-2.6.21-rc5.fds.orig/include/linux/sched.h	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/include/linux/sched.h	2007-03-31 12:29:28.000000000 -0700
@@ -379,6 +379,7 @@
 	atomic_t		count;
 	struct k_sigaction	action[_NSIG];
 	spinlock_t		siglock;
+	struct list_head        signalfd_list;
 };
 
 struct pacct_struct {
Index: linux-2.6.21-rc5.fds/kernel/fork.c
===================================================================
--- linux-2.6.21-rc5.fds.orig/kernel/fork.c	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/kernel/fork.c	2007-03-31 12:29:28.000000000 -0700
@@ -1424,8 +1424,10 @@
 	struct sighand_struct *sighand = data;
 
 	if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
-					SLAB_CTOR_CONSTRUCTOR)
+					SLAB_CTOR_CONSTRUCTOR) {
 		spin_lock_init(&sighand->siglock);
+		INIT_LIST_HEAD(&sighand->signalfd_list);
+	}
 }
 
 void __init proc_caches_init(void)
Index: linux-2.6.21-rc5.fds/include/linux/syscalls.h
===================================================================
--- linux-2.6.21-rc5.fds.orig/include/linux/syscalls.h	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/include/linux/syscalls.h	2007-03-31 12:29:28.000000000 -0700
@@ -602,6 +602,7 @@
 asmlinkage long sys_set_robust_list(struct robust_list_head __user *head,
 				    size_t len);
 asmlinkage long sys_getcpu(unsigned __user *cpu, unsigned __user *node, struct getcpu_cache __user *cache);
+asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask);
 
 int kernel_execve(const char *filename, char *const argv[], char *const envp[]);
 
Index: linux-2.6.21-rc5.fds/include/linux/signalfd.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.21-rc5.fds/include/linux/signalfd.h	2007-03-31 12:29:28.000000000 -0700
@@ -0,0 +1,97 @@
+/*
+ *  include/linux/signalfd.h
+ *
+ *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#ifndef _LINUX_SIGNALFD_H
+#define _LINUX_SIGNALFD_H
+
+
+struct signalfd_siginfo {
+	__u32 signo;
+	__s32 err;
+	__s32 code;
+	__u32 pid;
+	__u32 uid;
+	__s32 fd;
+	__u32 tid;
+	__u32 band;
+	__u32 overrun;
+	__u32 trapno;
+	__s32 status;
+	__s32 svint;
+	__u64 svptr;
+	__u64 utime;
+	__u64 stime;
+	__u64 addr;
+
+	/*
+	 * Pad strcture to 128 bytes. Remember to update the
+	 * pad size when you add new memebers. We use a fixed
+	 * size structure to avoid compatibility problems with
+	 * future versions, and we leave extra space for additional
+	 * members. We use fixed size members because this strcture
+	 * comes out of a read(2) and we really don't want to have
+	 * a compat on read(2).
+	 */
+	__u8 __pad[48];
+};
+
+
+#ifdef __KERNEL__
+
+#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.
+ */
+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);
+	}
+}
+
+#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)
+
+#endif /* CONFIG_SIGNALFD */
+
+#endif /* __KERNEL__ */
+
+#endif /* _LINUX_SIGNALFD_H */
+
Index: linux-2.6.21-rc5.fds/kernel/signal.c
===================================================================
--- linux-2.6.21-rc5.fds.orig/kernel/signal.c	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/kernel/signal.c	2007-03-31 12:29:28.000000000 -0700
@@ -26,6 +26,7 @@
 #include <linux/freezer.h>
 #include <linux/pid_namespace.h>
 #include <linux/nsproxy.h>
+#include <linux/signalfd.h>
 
 #include <asm/param.h>
 #include <asm/uaccess.h>
@@ -233,8 +234,7 @@
 
 /* Given the mask, find the first available signal that should be serviced. */
 
-static int
-next_signal(struct sigpending *pending, sigset_t *mask)
+int next_signal(struct sigpending *pending, sigset_t *mask)
 {
 	unsigned long i, *s, *m, x;
 	int sig = 0;
@@ -740,6 +740,12 @@
 	int ret = 0;
 
 	/*
+	 * Deliver the signal to listening signalfds. This must be called
+	 * with the sighand lock held.
+	 */
+	signalfd_notify(t, sig);
+
+	/*
 	 * fast-pathed signals for kernel-internal things like SIGSTOP
 	 * or SIGKILL.
 	 */
@@ -1401,6 +1407,11 @@
 		ret = 1;
 		goto out;
 	}
+	/*
+	 * Deliver the signal to listening signalfds. This must be called
+	 * with the sighand lock held.
+	 */
+	signalfd_notify(p, sig);
 
 	list_add_tail(&q->list, &p->pending.list);
 	sigaddset(&p->pending.signal, sig);
@@ -1444,6 +1455,11 @@
 		q->info.si_overrun++;
 		goto out;
 	} 
+	/*
+	 * Deliver the signal to listening signalfds. This must be called
+	 * with the sighand lock held.
+	 */
+	signalfd_notify(p, sig);
 
 	/*
 	 * Put this signal on the shared-pending queue.
@@ -2104,6 +2120,8 @@
 	/*
 	 * If you change siginfo_t structure, please be sure
 	 * this code is fixed accordingly.
+	 * Please remember to update the signalfd_copyinfo() function
+	 * inside fs/signalfd.c too, in case siginfo_t changes.
 	 * It should never copy any pad contained in the structure
 	 * to avoid security leaks, but must copy the generic
 	 * 3 ints plus the relevant union member.
Index: linux-2.6.21-rc5.fds/fs/exec.c
===================================================================
--- linux-2.6.21-rc5.fds.orig/fs/exec.c	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/fs/exec.c	2007-03-31 12:29:28.000000000 -0700
@@ -50,6 +50,7 @@
 #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>
@@ -581,6 +582,13 @@
 	int count;
 
 	/*
+	 * Tell all the sighand listeners that this sighand has
+	 * been detached. The signalfd_detach() function grabs the
+	 * sighand lock, if signal listeners are present on the sighand.
+	 */
+	signalfd_detach(tsk);
+
+	/*
 	 * If we don't share sighandlers, then we aren't sharing anything
 	 * and we can just re-use it all.
 	 */
@@ -756,8 +764,7 @@
 		spin_unlock(&oldsighand->siglock);
 		write_unlock_irq(&tasklist_lock);
 
-		if (atomic_dec_and_test(&oldsighand->count))
-			kmem_cache_free(sighand_cachep, oldsighand);
+		__cleanup_sighand(oldsighand);
 	}
 
 	BUG_ON(!thread_group_leader(tsk));
Index: linux-2.6.21-rc5.fds/kernel/exit.c
===================================================================
--- linux-2.6.21-rc5.fds.orig/kernel/exit.c	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/kernel/exit.c	2007-03-31 12:29:28.000000000 -0700
@@ -42,6 +42,7 @@
 #include <linux/audit.h> /* for audit_free() */
 #include <linux/resource.h>
 #include <linux/blkdev.h>
+#include <linux/signalfd.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -82,6 +83,14 @@
 	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);
Index: linux-2.6.21-rc5.fds/include/linux/signal.h
===================================================================
--- linux-2.6.21-rc5.fds.orig/include/linux/signal.h	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/include/linux/signal.h	2007-03-31 12:29:28.000000000 -0700
@@ -233,6 +233,7 @@
 	return sig <= _NSIG ? 1 : 0;
 }
 
+extern int next_signal(struct sigpending *pending, sigset_t *mask);
 extern int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p);
 extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *);
 extern long do_sigpending(void __user *, unsigned long);
Index: linux-2.6.21-rc5.fds/include/linux/Kbuild
===================================================================
--- linux-2.6.21-rc5.fds.orig/include/linux/Kbuild	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/include/linux/Kbuild	2007-03-31 12:29:28.000000000 -0700
@@ -190,6 +190,7 @@
 unifdef-y += errqueue.h
 unifdef-y += ethtool.h
 unifdef-y += eventpoll.h
+unifdef-y += signalfd.h
 unifdef-y += ext2_fs.h
 unifdef-y += ext3_fs.h
 unifdef-y += fb.h
Index: linux-2.6.21-rc5.fds/fs/Makefile
===================================================================
--- linux-2.6.21-rc5.fds.orig/fs/Makefile	2007-03-31 12:28:39.000000000 -0700
+++ linux-2.6.21-rc5.fds/fs/Makefile	2007-03-31 12:29:28.000000000 -0700
@@ -23,6 +23,7 @@
 obj-$(CONFIG_INOTIFY_USER)	+= inotify_user.o
 obj-$(CONFIG_EPOLL)		+= eventpoll.o
 obj-$(CONFIG_ANON_INODES)	+= anon_inodes.o
+obj-$(CONFIG_SIGNALFD)		+= signalfd.o
 obj-$(CONFIG_COMPAT)		+= compat.o compat_ioctl.o
 
 nfsd-$(CONFIG_NFSD)		:= nfsctl.o
Index: linux-2.6.21-rc5.fds/init/Kconfig
===================================================================
--- linux-2.6.21-rc5.fds.orig/init/Kconfig	2007-03-31 12:29:21.000000000 -0700
+++ linux-2.6.21-rc5.fds/init/Kconfig	2007-03-31 12:29:28.000000000 -0700
@@ -473,6 +473,16 @@
 	  Disabling this option will cause the kernel to be built without
 	  support for epoll family of system calls.
 
+config SIGNALFD
+	bool "Eanble signalfd() system call" if EMBEDDED
+	depends on ANON_INODES
+	default y
+	help
+	  Enable the signalfd() system call that allows to receive signals
+	  on a file descriptor.
+
+	  If unsure, say Y.
+
 config SHMEM
 	bool "Use full shmem filesystem" if EMBEDDED
 	default y

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [patch 2/13] signal/timer/event fds v9 - signalfd core ...
  2007-03-31 20:27 [patch 2/13] signal/timer/event fds v9 - signalfd core Davide Libenzi
@ 2007-03-31 21:07 ` Davide Libenzi
  0 siblings, 0 replies; 2+ messages in thread
From: Davide Libenzi @ 2007-03-31 21:07 UTC (permalink / raw)
  To: Linux Kernel Mailing List
  Cc: Andrew Morton, Linus Torvalds, Oleg Nesterov, Eric W. Biederman

On Sat, 31 Mar 2007, Davide Libenzi wrote:

> +config SIGNALFD
> +	bool "Eanble signalfd() system call" if EMBEDDED
              ^^^^^^
Alright ...



- Davide



^ permalink raw reply	[flat|nested] 2+ messages in thread

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