[PATCH] set sigio target to current->pid and only if not already set

Jamie Lokier
2003-10-09T01:52:43Z

Patch: f_setown-2.6.0-test6.patch

Dear Linus,

Two minor changes:

1. send_sigio() sends to a specific thread, _not_ a process.
(It can also send to a process group, but that's not relevant here).
This is useful, and should stay as it is.

Therefore it makes _no sense_ to call f_setown() with current->tgid.
Presently the kernel is inconsistent about it, with some places using
current->pid and some others using current->tgid.

This patch changes f_setown() calls to use current->pid.

2. In some places, f_setown() is called not at the user's direct request,
but as a side effect of another function. Specifically: dnotify and
file leases.

It is good to allow a program the flexibility to specify a different
pid than the default, using F_SETOWN. Presently they can do this after
the dnotify or lease call, but there is a small time window when it
will be temporarily set to current->tgid (which as pointed out above,
is not always right).

The window is avoidable if the program can use F_SETOWN prior to the
dnotify or lease call. This is exactly what the "force" argument to
f_setown() is for, and this patch changes it to zero in those callers.

This change is not likely to affect any existing programs.

Please apply.

-- Jamie

diff -urN --exclude-from=dontdiff orig-2.6.0-test6/fs/dnotify.c f_setown-2.6.0-test6/fs/dnotify.c
--- orig-2.6.0-test6/fs/dnotify.c 2003-09-13 21:21:25.000000000 +0100
+++ f_setown-2.6.0-test6/fs/dnotify.c 2003-10-09 01:49:13.000000000 +0100
@@ -92,7 +92,7 @@
prev = &odn->dn_next;
}

- error = f_setown(filp, current->tgid, 1);
+ error = f_setown(filp, current->pid, 0);
if (error)
goto out_free;

diff -urN --exclude-from=dontdiff orig-2.6.0-test6/fs/locks.c f_setown-2.6.0-test6/fs/locks.c
--- orig-2.6.0-test6/fs/locks.c 2003-09-30 05:40:50.000000000 +0100
+++ f_setown-2.6.0-test6/fs/locks.c 2003-10-09 01:49:37.000000000 +0100
@@ -1268,7 +1268,7 @@

locks_insert_lock(before, fl);

- error = f_setown(filp, current->tgid, 1);
+ error = f_setown(filp, current->pid, 0);
out_unlock:
unlock_kernel();
return error;
diff -urN --exclude-from=dontdiff orig-2.6.0-test6/kernel/futex.c f_setown-2.6.0-test6/kernel/futex.c
--- orig-2.6.0-test6/kernel/futex.c 2003-09-30 05:41:14.000000000 +0100
+++ f_setown-2.6.0-test6/kernel/futex.c 2003-10-09 01:52:37.000000000 +0100
@@ -500,7 +500,7 @@

if (signal) {
int err;
- err = f_setown(filp, current->tgid, 1);
+ err = f_setown(filp, current->pid, 1);
if (err < 0) {
put_unused_fd(ret);
put_filp(filp);