Hello everybody,
I found a problem in /proc/self/schedstat: a simple "cat" can give "wrong"
results.
/proc# cat self/schedstat
91117 26027 2
/proc# cat self/schedstat
90691 27872 2
/proc# cat self/schedstat
995483 15675 3
/proc# cat self/schedstat
478050 124422 3
/proc# cat self/schedstat
87912 21539 2
/proc# cat self/schedstat
81382 19722 2
/proc# cat self/schedstat
87999 119699 2
/proc# cat self/schedstat
87192 25990 2
/proc# cat self/schedstat
80114 15113 2
3
/proc# cat self/schedstat
93064 28817 2
/proc# cat self/schedstat
90834 22816 2
/proc# cat self/schedstat
87806 37581 2
/proc# cat self/schedstat
80187 20283 2
3
/proc#
Please note the extra newline and possible other digits.
A strace reveals that cat does
open("self/schedstat", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
read(3, "946533 98256 64\n", 4096) = 16
write(1, "946533 98256 64\n", 16) = 16
read(3, "8\n", 4096) = 2
write(1, "8\n", 2) = 2
read(3, "", 4096) = 0
close(3) = 0
close(1) = 0
exit_group(0) = ?
The simple fix would be to change the format in proc_pid_schedstat(), so
that it always returns the same number of bytes.
Or proc_info_read() gets changed - if less bytes than wanted (by userspace)
were returned, mark that file for returning EOF next time. But I fear that
that might break other entries that rely on getting repeatedly called.
Regards,
Phil
--
Versioning your /etc, /home or even your whole installation?
Try fsvs (fsvs.tigris.org)!
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
