aboutsummaryrefslogtreecommitdiff
path: root/fs/sysfs/file.c
diff options
context:
space:
mode:
authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2009-04-09 13:53:22 +0900
committerGreg Kroah-Hartman <gregkh@suse.de>2009-04-16 16:17:09 -0700
commit1af3557abdef34ee036a6de4cb79e24468544b8d (patch)
treef390d8d72bbba5302fcafb4c3666ac92469b488a /fs/sysfs/file.c
parentd094cbe998eb566d47552aa9d3c26c9123a7b858 (diff)
downloadvexpress-lsk-1af3557abdef34ee036a6de4cb79e24468544b8d.tar.gz
sysfs: sysfs poll keep the poll rule of regular file.
Currently, following test programs don't finished. % ruby -e ' Thread.new { sleep } File.read("/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies") ' strace expose the reason. ... open("/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies", O_RDONLY|O_LARGEFILE) = 3 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbf9fa6b8) = -1 ENOTTY (Inappropriate ioctl for device) fstat64(3, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0 _llseek(3, 0, [0], SEEK_CUR) = 0 select(4, [3], NULL, NULL, NULL) = 1 (in [3]) read(3, "1400000 1300000 1200000 1100000 1"..., 4096) = 62 select(4, [3], NULL, NULL, NULL Because Ruby (the scripting language) VM assume select system-call against regular file don't block. it because SUSv3 says "Regular files shall always poll TRUE for reading and writing". see http://www.opengroup.org/onlinepubs/009695399/functions/poll.html it seems valid assumption. But sysfs_poll() don't keep this rule although sysfs file can read and write always. This patch restore proper poll behavior to sysfs. /sys/block/md*/md/sync_action polling application and another sysfs updating sensitive application still can use POLLERR and POLLPRI. Cc: Neil Brown <neilb@suse.de> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/sysfs/file.c')
-rw-r--r--fs/sysfs/file.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 979e9379fb5..b1606e07b7a 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -446,11 +446,11 @@ static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
if (buffer->event != atomic_read(&od->event))
goto trigger;
- return 0;
+ return DEFAULT_POLLMASK;
trigger:
buffer->needs_read_fill = 1;
- return POLLERR|POLLPRI;
+ return DEFAULT_POLLMASK|POLLERR|POLLPRI;
}
void sysfs_notify_dirent(struct sysfs_dirent *sd)