[patch] thread-flock-2.5.38-A3

Ingo Molnar (mingo@elte.hu)
Wed, 25 Sep 2002 10:35:15 +0200 (CEST)


Ulrich found another small detail wrt. POSIX requirements for threads -
this time it's the recursion features (read-held lock being write-locked
means an upgrade if the same 'process' is the owner, means a deadlock if a
different 'process').

this requirement even makes some sense - the group of threads who own a
lock really own all rights to the lock as well.

the attached patch against BK-curr fixes this, all testcases pass now.
(inter-process testcases as well, which are not affected by this patch.)

(SIGURG and SIGIO semantics should also continue to work - there's some
more stuff we can optimize with the new pidhash in this area, but that's
for later.)

Ingo

--- linux/fs/locks.c.orig Wed Sep 25 10:28:26 2002
+++ linux/fs/locks.c Wed Sep 25 10:28:41 2002
@@ -252,7 +252,7 @@
return -ENOMEM;

fl->fl_file = filp;
- fl->fl_pid = current->pid;
+ fl->fl_pid = current->tgid;
fl->fl_flags = (cmd & LOCK_NB) ? FL_FLOCK : FL_FLOCK | FL_SLEEP;
fl->fl_type = type;
fl->fl_end = OFFSET_MAX;
@@ -308,7 +308,7 @@
fl->fl_end = OFFSET_MAX;

fl->fl_owner = current->files;
- fl->fl_pid = current->pid;
+ fl->fl_pid = current->tgid;
fl->fl_file = filp;
fl->fl_flags = FL_POSIX;
fl->fl_notify = NULL;
@@ -348,7 +348,7 @@
fl->fl_end = OFFSET_MAX;

fl->fl_owner = current->files;
- fl->fl_pid = current->pid;
+ fl->fl_pid = current->tgid;
fl->fl_file = filp;
fl->fl_flags = FL_POSIX;
fl->fl_notify = NULL;
@@ -377,7 +377,7 @@
return -ENOMEM;

fl->fl_owner = current->files;
- fl->fl_pid = current->pid;
+ fl->fl_pid = current->tgid;

fl->fl_file = filp;
fl->fl_flags = FL_LEASE;
@@ -669,7 +669,7 @@
int error;

fl.fl_owner = current->files;
- fl.fl_pid = current->pid;
+ fl.fl_pid = current->tgid;
fl.fl_file = filp;
fl.fl_flags = FL_POSIX | FL_ACCESS | FL_SLEEP;
fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
@@ -1241,7 +1241,7 @@
*before = fl;
list_add(&fl->fl_link, &file_lock_list);

- error = f_setown(filp, current->pid, 1);
+ error = f_setown(filp, current->tgid, 1);
out_unlock:
unlock_kernel();
return error;
@@ -1632,7 +1632,7 @@
lock.fl_start = 0;
lock.fl_end = OFFSET_MAX;
lock.fl_owner = owner;
- lock.fl_pid = current->pid;
+ lock.fl_pid = current->tgid;
lock.fl_file = filp;

if (filp->f_op && filp->f_op->lock != NULL) {

-
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