[PATCH] fs/locks.c: Fix posix locking for threaded tasks

From: Matthew Wilcox (willy@debian.org)
Date: Sun Jun 09 2002 - 21:48:43 EST

Saurabh Desai believes that locks created by threads should not conflict
with each other. I'm inclined to agree; I don't know why the test for
->fl_pid was added, but the comment suggests that whoever added it wasn't
sure either.

Frankly, I have no clue about the intended semantics for threads, and
SUS v3 does not offer any enlightenment. But it seems reasonable that
processes which share a files_struct should share locks. After all,
if one process closes the fd, they'll remove locks belonging to the
other process.

Here's a patch generated against 2.4; it also applies to 2.5.
Please apply.

===== fs/locks.c 1.9 vs edited =====
--- 1.9/fs/locks.c Mon Jun 3 18:49:43 2002
+++ edited/fs/locks.c Fri Jun 7 21:24:12 2002
@@ -380,15 +380,12 @@
- * Check whether two locks have the same owner
- * N.B. Do we need the test on PID as well as owner?
- * (Clone tasks should be considered as one "owner".)
+ * Locks are deemed to have the same owner if the tasks share files_struct.
 static inline int
 locks_same_owner(struct file_lock *fl1, struct file_lock *fl2)
- return (fl1->fl_owner == fl2->fl_owner) &&
- (fl1->fl_pid == fl2->fl_pid);
+ return (fl1->fl_owner == fl2->fl_owner);
 /* Remove waiter from blocker's block list.

Revolutions do not require corporate support.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

This archive was generated by hypermail 2b29 : Sat Jun 15 2002 - 22:00:15 EST