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Message-ID: <Pine.LNX.4.64.0609251735070.4749@alien.or.mcafeemobile.com>
Date: Mon, 25 Sep 2006 17:43:10 -0700 (PDT)
From: Davide Libenzi <davidel@...ilserver.org>
To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
cc: Andrew Morton <akpm@...l.org>,
Michael Kerrisk <michael.kerrisk@....net>
Subject: [patch] epoll_pwait for 2.6.18 ...
The attached patch implements the epoll_pwait system call, that extend the
event wait mechanism with the same logic ppoll and pselect do. The
definition of epoll_pwait is:
int epoll_pwait(int epfd, struct epoll_event *events, int maxevents,
int timeout, const sigset_t *sigmask, size_t sigsetsize);
The difference between the vanilla epoll_wait and epoll_pwait is that the
latter allows the caller to specify a signal mask to be set while waiting
for events. Hence epoll_pwait will wait until either one monitored event,
or an unmasked signal happen. If sigmask is NULL, the epoll_pwait system
call will act exactly like epoll_wait. For the POSIX definition of
pselect, information is available here:
http://www.opengroup.org/onlinepubs/009695399/functions/select.html
This patch goes over 2.6.18 and the epoll_pwait definition depends on
the TIF_RESTORE_SIGMASK bits.
Signed-off-by: Davide Libenzi <davidel@...ilserver.org>
- Davide
arch/i386/kernel/syscall_table.S | 1
fs/eventpoll.c | 55 ++++++++++++++++++++++++++++++++++++---
include/asm-i386/unistd.h | 3 +-
include/linux/syscalls.h | 3 ++
4 files changed, 58 insertions(+), 4 deletions(-)
diff -Nru linux-2.6.18/arch/i386/kernel/syscall_table.S linux-2.6.18.pepoll/arch/i386/kernel/syscall_table.S
--- linux-2.6.18/arch/i386/kernel/syscall_table.S 2006-09-19 20:42:06.000000000 -0700
+++ linux-2.6.18.pepoll/arch/i386/kernel/syscall_table.S 2006-09-25 16:20:02.000000000 -0700
@@ -317,3 +317,4 @@
.long sys_tee /* 315 */
.long sys_vmsplice
.long sys_move_pages
+ .long sys_epoll_pwait
diff -Nru linux-2.6.18/fs/eventpoll.c linux-2.6.18.pepoll/fs/eventpoll.c
--- linux-2.6.18/fs/eventpoll.c 2006-09-19 20:42:06.000000000 -0700
+++ linux-2.6.18.pepoll/fs/eventpoll.c 2006-09-25 16:11:32.000000000 -0700
@@ -105,6 +105,8 @@
/* Maximum msec timeout value storeable in a long int */
#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ)
+#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
+
struct epoll_filefd {
struct file *file;
@@ -497,7 +499,7 @@
*/
asmlinkage long sys_epoll_create(int size)
{
- int error, fd;
+ int error, fd = -1;
struct eventpoll *ep;
struct inode *inode;
struct file *file;
@@ -640,7 +642,6 @@
return error;
}
-#define MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
/*
* Implement the event wait interface for the eventpoll file. It is the kernel
@@ -657,7 +658,7 @@
current, epfd, events, maxevents, timeout));
/* The maximum number of event must be greater than zero */
- if (maxevents <= 0 || maxevents > MAX_EVENTS)
+ if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
return -EINVAL;
/* Verify that the area passed by the user is writeable */
@@ -699,6 +700,54 @@
}
+#ifdef TIF_RESTORE_SIGMASK
+
+/*
+ * Implement the event wait interface for the eventpoll file. It is the kernel
+ * part of the user space epoll_pwait(2).
+ */
+asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,
+ int maxevents, int timeout, const sigset_t __user *sigmask,
+ size_t sigsetsize)
+{
+ int error;
+ sigset_t ksigmask, sigsaved;
+
+ /*
+ * If the caller wants a certain signal mask to be set during the wait,
+ * we apply it here.
+ */
+ if (sigmask) {
+ if (sigsetsize != sizeof(sigset_t))
+ return -EINVAL;
+ if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
+ return -EFAULT;
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
+ error = sys_epoll_wait(epfd, events, maxevents, timeout);
+
+ /*
+ * If we changed the signal mask, we need to restore the original one.
+ * In case we've got a signal while waiting, we do not restore the signal
+ * mask yet, and we allow do_signal() to deliver the signal on the way back
+ * to userspace, before the signal mask is restored.
+ */
+ if (sigmask) {
+ if (error == -EINTR) {
+ memcpy(¤t->saved_sigmask, &sigsaved, sizeof(sigsaved));
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+ } else
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+ }
+
+ return error;
+}
+
+#endif /* #ifdef TIF_RESTORE_SIGMASK */
+
+
/*
* Creates the file descriptor to be used by the epoll interface.
*/
diff -Nru linux-2.6.18/include/asm-i386/unistd.h linux-2.6.18.pepoll/include/asm-i386/unistd.h
--- linux-2.6.18/include/asm-i386/unistd.h 2006-09-19 20:42:06.000000000 -0700
+++ linux-2.6.18.pepoll/include/asm-i386/unistd.h 2006-09-25 16:21:05.000000000 -0700
@@ -323,10 +323,11 @@
#define __NR_tee 315
#define __NR_vmsplice 316
#define __NR_move_pages 317
+#define __NR_epoll_pwait 318
#ifdef __KERNEL__
-#define NR_syscalls 318
+#define NR_syscalls 319
/*
* user-visible error numbers are in the range -1 - -128: see
diff -Nru linux-2.6.18/include/linux/syscalls.h linux-2.6.18.pepoll/include/linux/syscalls.h
--- linux-2.6.18/include/linux/syscalls.h 2006-09-19 20:42:06.000000000 -0700
+++ linux-2.6.18.pepoll/include/linux/syscalls.h 2006-09-25 16:11:32.000000000 -0700
@@ -430,6 +430,9 @@
struct epoll_event __user *event);
asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,
int maxevents, int timeout);
+asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,
+ int maxevents, int timeout, const sigset_t __user *sigmask,
+ size_t sigsetsize);
asmlinkage long sys_gethostname(char __user *name, int len);
asmlinkage long sys_sethostname(char __user *name, int len);
asmlinkage long sys_setdomainname(char __user *name, int len);
-
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