Author: trasz Date: Wed Feb 10 17:02:06 2010 New Revision: 203759 URL: http://svn.freebsd.org/changeset/base/203759
Log: Improve description for Giant and mention blocking inside interrupt threads. Modified: head/share/man/man9/locking.9 Modified: head/share/man/man9/locking.9 ============================================================================== --- head/share/man/man9/locking.9 Wed Feb 10 16:30:04 2010 (r203758) +++ head/share/man/man9/locking.9 Wed Feb 10 17:02:06 2010 (r203759) @@ -24,7 +24,7 @@ .\" .\" $FreeBSD$ .\" -.Dd January 29, 2010 +.Dd February 10, 2010 .Dt LOCKING 9 .Os .Sh NAME @@ -191,13 +191,16 @@ Giant is an instance of a mutex, with so .It It is recursive. .It -Drivers can request that Giant be locked around them, but this is -going away. -.It -You can sleep while it has recursed, but other recursive locks cannot. +Drivers and filesystems can request that Giant be locked around them +by not marking themselves MPSAFE. Note that infrastructure to do this +is slowly going away as non-MPSAFE drivers either became properly locked +or disappear. .It Giant must be locked first before other locks. .It +It is OK to hold Giant while performing unbounded sleep; in such case, +Giant will be dropped before sleeping and picked up after wakeup. +.It There are places in the kernel that drop Giant and pick it back up again. Sleep locks will do this before sleeping. @@ -315,6 +318,9 @@ If any caller above you has any mutex or rwlock, your sleep, will cause a panic. If the sleep only happens rarely it may be years before the bad code path is found. +.Pp +It is an error to do any operation that could result in unbounded sleep when +running inside an interrupt thread. .Ss Interaction table The following table shows what you can and can not do if you hold one of the synchronization primitives discussed here: _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
