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authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>2007-03-10 03:23:03 -0500
committerPaul Mackerras <paulus@samba.org>2007-03-16 16:37:28 +1100
commitf144e7c7272bf527c380bffaa5e789dc28a09d8d (patch)
tree18139c591b245d3f60bd074ca7321ed111722596 /arch/powerpc/kernel/process.c
parentdb98e0b434a6265c451ffe94ec0a29b8d0aaf587 (diff)
[POWERPC] Fix atomicity of TIF update in flush_thread()
Fix atomicity of TIF update in flush_thread() for powerpc Fixes it correctly with *_ti_thread_flag. Race : parent process executing : sys_ptrace() (lock_kernel()) (ptrace_get_task_struct(pid)) arch_ptrace() ptrace_detach() ptrace_disable(child); clear_singlestep(child); clear_tsk_thread_flag(child, TIF_SINGLESTEP); (which clears the TIF_SINGLESTEP flag atomically from a different process) (put_task_struct(child)) (unlock_kernel()) And at the same time, in the child process : sys_execve() do_execve() search_binary_handler() load_elf_binary() flush_old_exec() flush_thread() doing a non-atomic thread flag update Applies on 2.6.20. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/kernel/process.c')
-rw-r--r--arch/powerpc/kernel/process.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f3d4dd580dd..e53b2988d1b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -465,8 +465,13 @@ void flush_thread(void)
#ifdef CONFIG_PPC64
struct thread_info *t = current_thread_info();
- if (t->flags & _TIF_ABI_PENDING)
- t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
+ if (test_ti_thread_flag(t, TIF_ABI_PENDING)) {
+ clear_ti_thread_flag(t, TIF_ABI_PENDING);
+ if (test_ti_thread_flag(t, TIF_32BIT))
+ clear_ti_thread_flag(t, TIF_32BIT);
+ else
+ set_ti_thread_flag(t, TIF_32BIT);
+ }
#endif
discard_lazy_cpu_state();