Date: Fri, 19 Dec 2008 16:08:40 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: cvs-src-old@freebsd.org Subject: cvs commit: src/sys/kern kern_sysctl.c Message-ID: <200812191608.mBJG8xdS028397@repoman.freebsd.org>
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kib 2008-12-19 16:08:40 UTC
FreeBSD src repository
Modified files: (Branch: RELENG_7_1)
sys/kern kern_sysctl.c
Log:
SVN rev 186328 on 2008-12-19 16:08:40Z by kib
MFC r185983:
The userland_sysctl() function retries sysctl_root() until returned
error is not EAGAIN. Several sysctls that inspect another process use
p_candebug() for checking access right for the curproc. p_candebug()
returns EAGAIN for some reasons, in particular, for the process doing
exec() now. If execing process tries to lock Giant, we get a livelock,
because sysctl handlers are covered by Giant, and often do not sleep.
Break the livelock by dropping Giant and allowing other threads to
execute in the EAGAIN loop.
This commit does not merge the following change, as was discussed with jhb:
[Also, do not return EAGAIN from p_candebug() when process is executing,
use more appropriate EBUSY error.]
MFC r185987:
Uio_yield() already does DROP_GIANT/PICKUP_GIANT, no need to repeat this
around the call.
Approved by: re (kensmith)
Revision Changes Path
1.177.6.2 +6 -2 src/sys/kern/kern_sysctl.c
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