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v0.5.1
https://github.com/torvalds/linux
02 December 2023, 22:23:51 UTC
Revision 0f7e663dea7f0e22f3b2d07156c5e9d2e8656610 authored by Bodo Stroesser on 07 May 2005, 04:30:54 UTC, committed by Linus Torvalds on 07 May 2005, 05:09:30 UTC 
[PATCH] uml: Fix process exit race
 
tt-mode closes switch_pipes in exit_thread_tt and kills processes in
switch_to_tt, if the exit_state is EXIT_DEAD or EXIT_ZOMBIE.

In very rare cases the exiting process can be scheduled out after having set
exit_state and closed switch_pipes (from release_task it calls proc_pid_flush,
which might sleep).  If this process is to be restarted, UML failes in
switch_to_tt with:

   write of switch_pipe failed, err = 9

We fix this by closing switch_pipes not in exit_thread_tt, but later in
release_thread_tt.  Additionally, we set switch_pipe[0] = 0 after closing.
switch_to_tt must not kill "from" process depending on its exit_state, but
must kill it after release_thread was processed only, so it examines
switch_pipe[0] for its decision.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent b8bd022
History
Tip revision: 0f7e663dea7f0e22f3b2d07156c5e9d2e8656610 authored by Bodo Stroesser on 07 May 2005, 04:30:54 UTC
[PATCH] uml: Fix process exit race
Tip revision: 0f7e663
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