If epoll_wait returns -EFAULT, the event that was being returned when the
fault was encountered will be forgotten. This is not a big deal since
EFAULT will happen only if a buggy userspace program passes in a bad
address, in which case what happens later usually doesn't matter.
However, it is easy to remember the event for later, and this patch makes
a simple change to do that.
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ep_call_nested() (formerly ep_poll_safewake()) uses "current" (without
dereferencing it) to detect callback recursion, but it may be called from
irq context where the use of current is generally discouraged. It would
be better to use get_cpu() and put_cpu() to detect the callback recursion.
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix a bug inside the epoll's f_op->poll() code, that returns POLLIN even
though there are no actual ready monitored fds. The bug shows up if you
add an epoll fd inside another fd container (poll, select, epoll).
The problem is that callback-based wake ups used by epoll does not carry
(patches will follow, to fix this) any information about the events that
actually happened. So the callback code, since it can't call the file*
->poll() inside the callback, chains the file* into a ready-list.
So, suppose you added an fd with EPOLLOUT only, and some data shows up on
the fd, the file* mapped by the fd will be added into the ready-list (via
wakeup callback). During normal epoll_wait() use, this condition is
sorted out at the time we're actually able to call the file*'s
f_op->poll().
Inside the old epoll's f_op->poll() though, only a quick check
!list_empty(ready-list) was performed, and this could have led to
reporting POLLIN even though no ready fds would show up at a following
epoll_wait(). In order to correctly report the ready status for an epoll
fd, the ready-list must be checked to see if any really available fd+event
would be ready in a following epoll_wait().
Operation (calling f_op->poll() from inside f_op->poll()) that, like wake
ups, must be handled with care because of the fact that epoll fds can be
added to other epoll fds.
Test code:
/*
* epoll_test by Davide Libenzi (Simple code to test epoll internals)
* Copyright (C) 2008 Davide Libenzi
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Davide Libenzi <davidel@xmailserver.org>
*
*/
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <limits.h>
#include <poll.h>
#include <sys/epoll.h>
#include <sys/wait.h>
#define EPWAIT_TIMEO (1 * 1000)
#ifndef POLLRDHUP
#define POLLRDHUP 0x2000
#endif
#define EPOLL_MAX_CHAIN 100L
#define EPOLL_TF_LOOP (1 << 0)
struct epoll_test_cfg {
long size;
long flags;
};
static int xepoll_create(int n) {
int epfd;
if ((epfd = epoll_create(n)) == -1) {
perror("epoll_create");
exit(2);
}
return epfd;
}
static void xepoll_ctl(int epfd, int cmd, int fd, struct epoll_event *evt) {
if (epoll_ctl(epfd, cmd, fd, evt) < 0) {
perror("epoll_ctl");
exit(3);
}
}
static void xpipe(int *fds) {
if (pipe(fds)) {
perror("pipe");
exit(4);
}
}
static pid_t xfork(void) {
pid_t pid;
if ((pid = fork()) == (pid_t) -1) {
perror("pipe");
exit(5);
}
return pid;
}
static int run_forked_proc(int (*proc)(void *), void *data) {
int status;
pid_t pid;
if ((pid = xfork()) == 0)
exit((*proc)(data));
if (waitpid(pid, &status, 0) != pid) {
perror("waitpid");
return -1;
}
return WIFEXITED(status) ? WEXITSTATUS(status): -2;
}
static int check_events(int fd, int timeo) {
struct pollfd pfd;
fprintf(stdout, "Checking events for fd %d\n", fd);
memset(&pfd, 0, sizeof(pfd));
pfd.fd = fd;
pfd.events = POLLIN | POLLOUT;
if (poll(&pfd, 1, timeo) < 0) {
perror("poll()");
return 0;
}
if (pfd.revents & POLLIN)
fprintf(stdout, "\tPOLLIN\n");
if (pfd.revents & POLLOUT)
fprintf(stdout, "\tPOLLOUT\n");
if (pfd.revents & POLLERR)
fprintf(stdout, "\tPOLLERR\n");
if (pfd.revents & POLLHUP)
fprintf(stdout, "\tPOLLHUP\n");
if (pfd.revents & POLLRDHUP)
fprintf(stdout, "\tPOLLRDHUP\n");
return pfd.revents;
}
static int epoll_test_tty(void *data) {
int epfd, ifd = fileno(stdin), res;
struct epoll_event evt;
if (check_events(ifd, 0) != POLLOUT) {
fprintf(stderr, "Something is cooking on STDIN (%d)\n", ifd);
return 1;
}
epfd = xepoll_create(1);
fprintf(stdout, "Created epoll fd (%d)\n", epfd);
memset(&evt, 0, sizeof(evt));
evt.events = EPOLLIN;
xepoll_ctl(epfd, EPOLL_CTL_ADD, ifd, &evt);
if (check_events(epfd, 0) & POLLIN) {
res = epoll_wait(epfd, &evt, 1, 0);
if (res == 0) {
fprintf(stderr, "Epoll fd (%d) is ready when it shouldn't!\n",
epfd);
return 2;
}
}
return 0;
}
static int epoll_wakeup_chain(void *data) {
struct epoll_test_cfg *tcfg = data;
int i, res, epfd, bfd, nfd, pfds[2];
pid_t pid;
struct epoll_event evt;
memset(&evt, 0, sizeof(evt));
evt.events = EPOLLIN;
epfd = bfd = xepoll_create(1);
for (i = 0; i < tcfg->size; i++) {
nfd = xepoll_create(1);
xepoll_ctl(bfd, EPOLL_CTL_ADD, nfd, &evt);
bfd = nfd;
}
xpipe(pfds);
if (tcfg->flags & EPOLL_TF_LOOP)
{
xepoll_ctl(bfd, EPOLL_CTL_ADD, epfd, &evt);
/*
* If we're testing for loop, we want that the wakeup
* triggered by the write to the pipe done in the child
* process, triggers a fake event. So we add the pipe
* read size with EPOLLOUT events. This will trigger
* an addition to the ready-list, but no real events
* will be there. The the epoll kernel code will proceed
* in calling f_op->poll() of the epfd, triggering the
* loop we want to test.
*/
evt.events = EPOLLOUT;
}
xepoll_ctl(bfd, EPOLL_CTL_ADD, pfds[0], &evt);
/*
* The pipe write must come after the poll(2) call inside
* check_events(). This tests the nested wakeup code in
* fs/eventpoll.c:ep_poll_safewake()
* By having the check_events() (hence poll(2)) happens first,
* we have poll wait queue filled up, and the write(2) in the
* child will trigger the wakeup chain.
*/
if ((pid = xfork()) == 0) {
sleep(1);
write(pfds[1], "w", 1);
exit(0);
}
res = check_events(epfd, 2000) & POLLIN;
if (waitpid(pid, NULL, 0) != pid) {
perror("waitpid");
return -1;
}
return res;
}
static int epoll_poll_chain(void *data) {
struct epoll_test_cfg *tcfg = data;
int i, res, epfd, bfd, nfd, pfds[2];
pid_t pid;
struct epoll_event evt;
memset(&evt, 0, sizeof(evt));
evt.events = EPOLLIN;
epfd = bfd = xepoll_create(1);
for (i = 0; i < tcfg->size; i++) {
nfd = xepoll_create(1);
xepoll_ctl(bfd, EPOLL_CTL_ADD, nfd, &evt);
bfd = nfd;
}
xpipe(pfds);
if (tcfg->flags & EPOLL_TF_LOOP)
{
xepoll_ctl(bfd, EPOLL_CTL_ADD, epfd, &evt);
/*
* If we're testing for loop, we want that the wakeup
* triggered by the write to the pipe done in the child
* process, triggers a fake event. So we add the pipe
* read size with EPOLLOUT events. This will trigger
* an addition to the ready-list, but no real events
* will be there. The the epoll kernel code will proceed
* in calling f_op->poll() of the epfd, triggering the
* loop we want to test.
*/
evt.events = EPOLLOUT;
}
xepoll_ctl(bfd, EPOLL_CTL_ADD, pfds[0], &evt);
/*
* The pipe write mush come before the poll(2) call inside
* check_events(). This tests the nested f_op->poll calls code in
* fs/eventpoll.c:ep_eventpoll_poll()
* By having the pipe write(2) happen first, we make the kernel
* epoll code to load the ready lists, and the following poll(2)
* done inside check_events() will test nested poll code in
* ep_eventpoll_poll().
*/
if ((pid = xfork()) == 0) {
write(pfds[1], "w", 1);
exit(0);
}
sleep(1);
res = check_events(epfd, 1000) & POLLIN;
if (waitpid(pid, NULL, 0) != pid) {
perror("waitpid");
return -1;
}
return res;
}
int main(int ac, char **av) {
int error;
struct epoll_test_cfg tcfg;
fprintf(stdout, "\n********** Testing TTY events\n");
error = run_forked_proc(epoll_test_tty, NULL);
fprintf(stdout, error == 0 ?
"********** OK\n": "********** FAIL (%d)\n", error);
tcfg.size = 3;
tcfg.flags = 0;
fprintf(stdout, "\n********** Testing short wakeup chain\n");
error = run_forked_proc(epoll_wakeup_chain, &tcfg);
fprintf(stdout, error == POLLIN ?
"********** OK\n": "********** FAIL (%d)\n", error);
tcfg.size = EPOLL_MAX_CHAIN;
tcfg.flags = 0;
fprintf(stdout, "\n********** Testing long wakeup chain (HOLD ON)\n");
error = run_forked_proc(epoll_wakeup_chain, &tcfg);
fprintf(stdout, error == 0 ?
"********** OK\n": "********** FAIL (%d)\n", error);
tcfg.size = 3;
tcfg.flags = 0;
fprintf(stdout, "\n********** Testing short poll chain\n");
error = run_forked_proc(epoll_poll_chain, &tcfg);
fprintf(stdout, error == POLLIN ?
"********** OK\n": "********** FAIL (%d)\n", error);
tcfg.size = EPOLL_MAX_CHAIN;
tcfg.flags = 0;
fprintf(stdout, "\n********** Testing long poll chain (HOLD ON)\n");
error = run_forked_proc(epoll_poll_chain, &tcfg);
fprintf(stdout, error == 0 ?
"********** OK\n": "********** FAIL (%d)\n", error);
tcfg.size = 3;
tcfg.flags = EPOLL_TF_LOOP;
fprintf(stdout, "\n********** Testing loopy wakeup chain (HOLD ON)\n");
error = run_forked_proc(epoll_wakeup_chain, &tcfg);
fprintf(stdout, error == 0 ?
"********** OK\n": "********** FAIL (%d)\n", error);
tcfg.size = 3;
tcfg.flags = EPOLL_TF_LOOP;
fprintf(stdout, "\n********** Testing loopy poll chain (HOLD ON)\n");
error = run_forked_proc(epoll_poll_chain, &tcfg);
fprintf(stdout, error == 0 ?
"********** OK\n": "********** FAIL (%d)\n", error);
return 0;
}
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a driver for Intersil's ISL29003 ambient light sensor device plus some
documentation. Inspired by tsl2550.c, a driver for a similar device.
It is put in drivers/misc for now until the industrial I/O framework gets
merged.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change hpilo open and close logic to spin for 10usec between checking device,
rather than every usec.
Because the loop is coded to take up to 10ms, it seemed prudent to
increase the interval between polling the device, to reduce the load on
the system and allow more other work to happen.
Signed-off-by: David Altobelli <david.altobelli@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The GPIO API is supposed to return 0 or a negative error code,
but the SSB GPIO functions return the bitmask of the GPIO register.
Fix this by ignoring the bitmask and always returning 0. The SSB GPIO functions can't fail.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that the filesystem freeze operation has been elevated to the VFS, and
is just an ioctl away, some sort of safety net for unintentionally frozen
root filesystems may be in order.
The timeout thaw originally proposed did not get merged, but perhaps
something like this would be useful in emergencies.
For example, freeze /path/to/mountpoint may freeze your root filesystem if
you forgot that you had that unmounted.
I chose 'j' as the last remaining character other than 'h' which is sort
of reserved for help (because help is generated on any unknown character).
I've tested this on a non-root fs with multiple (nested) freezers, as well
as on a system rendered unresponsive due to a frozen root fs.
[randy.dunlap@oracle.com: emergency thaw only if CONFIG_BLOCK enabled]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Takashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tfour 4 redundant if-conditions in function __rb_erase_color() in
lib/rbtree.c are removed.
In pseudo-source-code, the structure of the code is as follows:
if ((!A || B) && (!C || D)) {
.
.
.
} else {
if (!C || D) {//if this is true, it implies: (A == true) && (B == false)
if (A) {//hence this always evaluates to 'true'...
.
}
.
//at this point, C always becomes true, because of:
__rb_rotate_right/left();
//and:
other = parent->rb_right/left;
}
.
.
if (C) {//...and this too !
.
}
}
Signed-off-by: Wolfram Strepp <wstrepp@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
MAJOR_NR isn't needed anymore since very early 2.5 kernels.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make the following header file changes:
- remove arch ifdefs and asm/suspend.h from linux/suspend.h
- add asm/suspend.h to disk.c (for arch_prepare_suspend())
- add linux/io.h to swsusp.c (for ioremap())
- x86 32/64 bit compile fixes
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert alpha architecture to use u64 as unsigned long long. This is
being done so that (a) all arches use u64 as unsigned long long and (b)
printk of a u64 as %ll[ux] will not generate format warnings by gcc.
The only gcc cross-compiler that I have is 4.0.2, which generates errors
about miscompiling __weak references, so I have commented out that line in
compiler-gcc4.h so that most of these compile, but more builds and real
machine testing would be Real Good.
[akpm@linux-foundation.org: fix warning]
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
From: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- "_local" versions of xchg/cmpxchg functions duplicate code
of non-local ones (quite a few pages of assembler), except
memory barriers. We can generate these two variants from a
single header file using simple macros;
- convert xchg macro back to inline function using always_inline
attribute;
- use proper argument types for cmpxchg_u8/u16 functions
to fix a problem with negative arguments.
Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tony Battersby
Davide Libenzi
Daniel Mack
David Altobelli
Harvey Harrison
Cyrill Gorcunov
Hannes Eder
Michael Buesch
H Hartley Sweeten
FUJITA Tomonori
Eric Sandeen
Wolfram Strepp
J. R. Okajima
WANG Cong
Christoph Hellwig
Magnus Damm
Randy Dunlap
Ivan Kokshaysky
Cheng Renquan