Commit b611967d authored by Davide Libenzi's avatar Davide Libenzi Committed by Linus Torvalds
Browse files

[PATCH] epoll_pwait() 

Implement 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



Signed-off-by: default avatarDavide Libenzi <davidel@xmailserver.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 0f836e5f

arch/i386/kernel/syscall_table.S

+1 −0
Original line number Diff line number Diff line
@@ -318,3 +318,4 @@ ENTRY(sys_call_table) 
	.long sys_vmsplice

	.long sys_move_pages

	.long sys_getcpu

	.long sys_epoll_pwait

fs/eventpoll.c

+53 −3
Original line number Diff line number Diff line
@@ -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 @@ void eventpoll_release_file(struct file *file) 
 */

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 @@ eexit_1: 
	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 @@ asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events, 
		     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 +700,55 @@ eexit_1: 
}





#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(&current->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.

 */

include/asm-i386/unistd.h

+2 −1
Original line number Diff line number Diff line
@@ -324,10 +324,11 @@ 
#define __NR_vmsplice		316

#define __NR_move_pages		317

#define __NR_getcpu		318

#define __NR_epoll_pwait	319



#ifdef __KERNEL__



#define NR_syscalls 319

#define NR_syscalls 320

#include <linux/err.h>



/*

include/linux/syscalls.h

+4 −0
Original line number Diff line number Diff line
@@ -431,6 +431,10 @@ asmlinkage long sys_epoll_ctl(int epfd, int op, int fd, 
				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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