Retrieve multiple per-process signals through a file descriptor. The mask
of signals can be changed at any time. Also, the compat code can be kept
very simple.
Signed-off-by: Davi E. M. Arnaut <[EMAIL PROTECTED]>
---
fs/pollfs/Makefile | 2
fs/pollfs/signal.c | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++
init/Kconfig | 7 ++
3 files changed, 153 insertions(+)
Index: linux-2.6/fs/pollfs/signal.c
===================================================================
--- /dev/null
+++ linux-2.6/fs/pollfs/signal.c
@@ -0,0 +1,144 @@
+/*
+ * sigtimedwait4, retrieve multiple signals with one call.
+ *
+ * Copyright (C) 2007 Davi E. M. Arnaut
+ *
+ * Licensed under the GNU GPL. See the file COPYING for details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/wait.h>
+#include <asm/uaccess.h>
+#include <linux/poll.h>
+#include <linux/pollfs_fs.h>
+#include <linux/signal.h>
+
+struct pfs_signal {
+ sigset_t set;
+ spinlock_t lock;
+ struct task_struct *task;
+ struct pfs_file file;
+};
+
+static void inline sigset_adjust(sigset_t *set)
+{
+ /* SIGKILL and SIGSTOP cannot be caught, blocked, or ignored */
+ sigdelsetmask(set, sigmask(SIGKILL) | sigmask(SIGSTOP));
+
+ /* Signals we don't want to dequeue */
+ signotset(set);
+}
+
+static ssize_t read(struct pfs_signal *evs, siginfo_t __user *infoup)
+{
+ int signo;
+ siginfo_t info;
+
+ signo = dequeue_signal_lock(evs->task, &evs->set, &info);
+ if (!signo)
+ return -EAGAIN;
+
+ if (copy_siginfo_to_user(infoup, &info))
+ return -EFAULT;
+
+ return 0;
+}
+
+static ssize_t write(struct pfs_signal *evs, const sigset_t __user *uset)
+{
+ sigset_t set;
+
+ if (copy_from_user(&set, uset, sizeof(sigset_t)))
+ return -EFAULT;
+
+ sigset_adjust(&set);
+
+ spin_lock_irq(&evs->lock);
+ sigemptyset(&evs->set);
+ sigorsets(&evs->set, &evs->set, &set);
+ spin_unlock_irq(&evs->lock);
+
+ return 0;
+}
+
+static int poll(struct pfs_signal *evs)
+{
+ int ret = 0;
+ sigset_t pending;
+ unsigned long flags;
+
+ rcu_read_lock();
+
+ if (!lock_task_sighand(evs->task, &flags))
+ goto out_unlock;
+
+ sigorsets(&pending, &evs->task->pending.signal,
+ &evs->task->signal->shared_pending.signal);
+
+ unlock_task_sighand(evs->task, &flags);
+
+ spin_lock_irqsave(&evs->lock, flags);
+ signandsets(&pending, &pending, &evs->set);
+ spin_unlock_irqrestore(&evs->lock, flags);
+
+ if (!sigisemptyset(&pending))
+ ret = POLLIN;
+
+out_unlock:
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static int release(struct pfs_signal *evs)
+{
+ put_task_struct(evs->task);
+ kfree(evs);
+
+ return 0;
+}
+
+static const struct pfs_operations signal_ops = {
+ .read = PFS_READ(read, struct pfs_signal, siginfo_t),
+ .write = PFS_WRITE(write, struct pfs_signal, sigset_t),
+ .poll = PFS_POLL(poll, struct pfs_signal),
+ .release = PFS_RELEASE(release, struct pfs_signal),
+ .rsize = sizeof(siginfo_t),
+ .wsize = sizeof(sigset_t),
+};
+
+asmlinkage long sys_plsignal(const sigset_t __user *uset)
+{
+ long error;
+ struct pfs_signal *evs;
+
+ evs = kmalloc(sizeof(*evs), GFP_KERNEL);
+ if (!evs)
+ return -ENOMEM;
+
+ if (copy_from_user(&evs->set, uset, sizeof(sigset_t))) {
+ kfree(evs);
+ return -EFAULT;
+ }
+
+ spin_lock_init(&evs->lock);
+
+ evs->task = current;
+ get_task_struct(current);
+
+ sigset_adjust(&evs->set);
+
+ evs->file.data = evs;
+ evs->file.fops = &signal_ops;
+ evs->file.wait = &evs->task->sigwait;
+
+ error = pfs_open(&evs->file);
+ if (error < 0)
+ release(evs);
+
+ return error;
+}
Index: linux-2.6/fs/pollfs/Makefile
===================================================================
--- linux-2.6.orig/fs/pollfs/Makefile
+++ linux-2.6/fs/pollfs/Makefile
@@ -1,2 +1,4 @@
obj-$(CONFIG_POLLFS) += pollfs.o
pollfs-y := file.o
+
+pollfs-$(CONFIG_POLLFS_SIGNAL) += signal.o
Index: linux-2.6/init/Kconfig
===================================================================
--- linux-2.6.orig/init/Kconfig
+++ linux-2.6/init/Kconfig
@@ -469,6 +469,13 @@ config POLLFS
help
Pollfs support
+config POLLFS_SIGNAL
+ bool "Enable pollfs signal" if EMBEDDED
+ default y
+ depends on POLLFS
+ help
+ Pollable signal support
+
config SHMEM
bool "Use full shmem filesystem" if EMBEDDED
default y
--
-
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