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| author | Tejun Heo <tj@kernel.org> | 2013-01-23 09:31:01 -0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-01-23 09:31:01 -0800 |
| commit | c14afb82ffff5903a701a9fb737ac20f36d1f755 (patch) | |
| tree | 304dcc7b1d7b9a5f564f7e978228e61ef41fbef2 /arch/x86/kernel/step.c | |
| parent | 0fdff3ec6d87856cdcc99e69cf42143fdd6c56b4 (diff) | |
| parent | 1d8549085377674224bf30a368284c391a3ce40e (diff) | |
| download | olio-linux-3.10-c14afb82ffff5903a701a9fb737ac20f36d1f755.tar.xz olio-linux-3.10-c14afb82ffff5903a701a9fb737ac20f36d1f755.zip | |
Merge branch 'master' into for-3.9-async
To receive f56c3196f251012de9b3ebaff55732a9074fdaae ("async: fix
__lowest_in_progress()").
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'arch/x86/kernel/step.c')
| -rw-r--r-- | arch/x86/kernel/step.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index cd3b2438a98..9b4d51d0c0d 100644 --- a/arch/x86/kernel/step.c +++ b/arch/x86/kernel/step.c @@ -165,10 +165,11 @@ void set_task_blockstep(struct task_struct *task, bool on) * Ensure irq/preemption can't change debugctl in between. * Note also that both TIF_BLOCKSTEP and debugctl should * be changed atomically wrt preemption. - * FIXME: this means that set/clear TIF_BLOCKSTEP is simply - * wrong if task != current, SIGKILL can wakeup the stopped - * tracee and set/clear can play with the running task, this - * can confuse the next __switch_to_xtra(). + * + * NOTE: this means that set/clear TIF_BLOCKSTEP is only safe if + * task is current or it can't be running, otherwise we can race + * with __switch_to_xtra(). We rely on ptrace_freeze_traced() but + * PTRACE_KILL is not safe. */ local_irq_disable(); debugctl = get_debugctlmsr(); |