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| author | Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> | 2007-03-10 08:19:49 (GMT) |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2007-03-10 08:19:49 (GMT) |
| commit | c0a79b229ac0e3a96fc00d5be65a498ceb06ef63 (patch) | |
| tree | 5eda8f742f1480abf16952d6ba820be6a95d29b4 | |
| parent | 63abdcdc021063bf1cfcddfd3c1a14a761539807 (diff) | |
| download | linux-c0a79b229ac0e3a96fc00d5be65a498ceb06ef63.tar.xz | |
[SPARC64]: Fix atomicity of TIF update in flush_thread()
Fix atomicity of TIF update in flush_thread() for sparc64
Fixes correctly the race by using *_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
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | arch/sparc64/kernel/process.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/sparc64/kernel/process.c b/arch/sparc64/kernel/process.c index 7d75cd4..b291060 100644 --- a/arch/sparc64/kernel/process.c +++ b/arch/sparc64/kernel/process.c @@ -413,8 +413,13 @@ void flush_thread(void) struct thread_info *t = current_thread_info(); struct mm_struct *mm; - 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); + } mm = t->task->mm; if (mm) |