d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Reword descriptions of asserting locks held without WITNESS.

Browse Source 
This corrects an error in r296947 in that it is not possible to assert
which thread holds a shared (or read) lock, but it is possible to assert
that one is held.  Just not very useful.

MFC after:	1 week
Submitted by:	wblock, jhb
Reviewed by:	kib (earlier version), jhb, wblock
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D5659
This commit is contained in:
Bryan Drewery 2016-03-29 16:07:51 +00:00
parent 2dfe93f0ab
commit a23b48fee5
2 changed files with 21 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
share/man/man9/rwlock.9
View File

@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd December 13, 2014
.Dd March 28, 2016
.Dt RWLOCK 9
.Os
.Sh NAME
@ -313,18 +313,19 @@ facility was written by
This manual page was written by
.An "Gleb Smirnoff" .
.Sh BUGS
If
A kernel without
.Dv WITNESS
is not included in the kernel,
then it is impossible to assert that the current thread does or does not
hold a read lock.
In the
.Pf non- Dv WITNESS
case, the
cannot assert whether the current thread does or does not hold a read lock.
.Dv RA_LOCKED
and
.Dv RA_RLOCKED
assertions merely check that some thread holds a read lock.
can only assert that
.Em any
thread holds a read lock.
They cannot ensure that the current thread holds a read lock.
Further,
.Dv RA_UNLOCKED
can only assert that the current thread does not hold a write lock.
.Pp
Reader/writer is a bit of an awkward name.
An

17
share/man/man9/sx.9
View File

@ -26,7 +26,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd March 16, 2016
.Dd March 28, 2016
.Dt SX 9
.Os
.Sh NAME
@ -320,11 +320,16 @@ end up sleeping while holding a mutex, which is not allowed.
.Xr rwlock 9 ,
.Xr sema 9
.Sh BUGS
In the
.No non- Ns Dv WITNESS
case, the
A kernel without
.Dv WITNESS
cannot assert whether the current thread does or does not hold a shared lock.
.Dv SA_LOCKED
and
.Dv SA_SLOCKED
assertions merely check that some thread holds a shared lock.
They do not ensure that the current thread holds a shared lock.
can only assert that
.Em any
thread holds a shared lock.
They cannot ensure that the current thread holds a shared lock.
Further,
.Dv SA_UNLOCKED
can only assert that the current thread does not hold an exclusive lock.