The attached patch implements the pepoll_wait system call, that extend the
event wait mechanism with the same logic ppoll and pselect do. The definition
of pepoll_wait is:
int pepoll_wait(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 pepoll_wait is that the
latter allows the caller to specify a signal mask to be set while waiting for
events. Hence pepoll_wait will wait until either one monitored event, or an
unmasked signal happen. If sigmask is NULL, the pepoll_wait 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 2.6.15-mm4 and depends on the TIF_RESTORE_SIGMASK bits.
Signed-off-by: Davide Libenzi <[email protected]>
- Davide
arch/i386/kernel/syscall_table.S | 1
fs/eventpoll.c | 58 ++++++++++++++++++++++++++++++++++-----
include/asm-i386/unistd.h | 3 +-
include/linux/syscalls.h | 3 ++
4 files changed, 57 insertions(+), 8 deletions(-)
diff -Nru linux-2.6.15/arch/i386/kernel/syscall_table.S linux-2.6.15.mod/arch/i386/kernel/syscall_table.S
--- linux-2.6.15/arch/i386/kernel/syscall_table.S 2006-01-17 17:11:12.000000000 -0800
+++ linux-2.6.15.mod/arch/i386/kernel/syscall_table.S 2006-01-17 17:11:59.000000000 -0800
@@ -310,3 +310,4 @@
.long sys_pselect6
.long sys_ppoll
.long sys_unshare /* 310 */
+ .long sys_pepoll_wait
diff -Nru linux-2.6.15/fs/eventpoll.c linux-2.6.15.mod/fs/eventpoll.c
--- linux-2.6.15/fs/eventpoll.c 2006-01-17 17:11:14.000000000 -0800
+++ linux-2.6.15.mod/fs/eventpoll.c 2006-01-17 17:11:59.000000000 -0800
@@ -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;
@@ -649,24 +651,25 @@
return error;
}
-#define MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
/*
* Implement the event wait interface for the eventpoll file. It is the kernel
- * part of the user space epoll_wait(2).
+ * part of the user space pepoll_wait(2).
*/
-asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,
- int maxevents, int timeout)
+asmlinkage long sys_pepoll_wait(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;
struct file *file;
struct eventpoll *ep;
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d)\n",
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_pepoll_wait(%d, %p, %d, %d)\n",
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 */
@@ -695,13 +698,41 @@
*/
ep = file->private_data;
+ /*
+ * 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))
+ goto eexit_2;
+ error = -EFAULT;
+ if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
+ goto eexit_2;
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
/* Time to fish for events ... */
error = ep_poll(ep, 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 (error == -EINTR) {
+ if (sigmask) {
+ memcpy(¤t->saved_sigmask, &sigsaved, sizeof(sigsaved));
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+ }
+ } else if (sigmask)
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+
eexit_2:
fput(file);
eexit_1:
- DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d) = %d\n",
+ DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_pepoll_wait(%d, %p, %d, %d) = %d\n",
current, epfd, events, maxevents, timeout, error));
return error;
@@ -709,6 +740,19 @@
/*
+ * Implement the event wait interface for the eventpoll file. It is the kernel
+ * part of the user space epoll_wait(2). This just calls the super-sister
+ * sys_pepoll_wait() without signal parameters.
+ */
+asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,
+ int maxevents, int timeout)
+{
+
+ return sys_pepoll_wait(epfd, events, maxevents, timeout, NULL, 0);
+}
+
+
+/*
* Creates the file descriptor to be used by the epoll interface.
*/
static int ep_getfd(int *efd, struct inode **einode, struct file **efile,
diff -Nru linux-2.6.15/include/asm-i386/unistd.h linux-2.6.15.mod/include/asm-i386/unistd.h
--- linux-2.6.15/include/asm-i386/unistd.h 2006-01-17 17:11:14.000000000 -0800
+++ linux-2.6.15.mod/include/asm-i386/unistd.h 2006-01-17 17:11:59.000000000 -0800
@@ -316,8 +316,9 @@
#define __NR_pselect6 308
#define __NR_ppoll 309
#define __NR_unshare 310
+#define __NR_pepoll_wait 311
-#define NR_syscalls 311
+#define NR_syscalls 312
/*
* user-visible error numbers are in the range -1 - -128: see
diff -Nru linux-2.6.15/include/linux/syscalls.h linux-2.6.15.mod/include/linux/syscalls.h
--- linux-2.6.15/include/linux/syscalls.h 2006-01-17 17:11:15.000000000 -0800
+++ linux-2.6.15.mod/include/linux/syscalls.h 2006-01-17 17:12:59.000000000 -0800
@@ -428,6 +428,9 @@
struct epoll_event __user *event);
asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,
int maxevents, int timeout);
+asmlinkage long sys_pepoll_wait(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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