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authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>2007-03-10 00:19:49 -0800
committerDavid S. Miller <davem@davemloft.net>2007-03-10 00:19:49 -0800
commitc0a79b229ac0e3a96fc00d5be65a498ceb06ef63 (patch)
tree5eda8f742f1480abf16952d6ba820be6a95d29b4
parent63abdcdc021063bf1cfcddfd3c1a14a761539807 (diff)
[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.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/sparc64/kernel/process.c b/arch/sparc64/kernel/process.c
index 7d75cd4eb297..b291060c25a6 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)