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| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-01-29 11:33:37 +1100 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-01-29 11:33:37 +1100 |
| commit | dfd0436ad0ce139467b124c646fa65ee2635e14a (patch) | |
| tree | abf9d83c704417cdd484243c12aeffee6b185aba /arch/x86/kernel/step.c | |
| parent | b9818c3312da66f4b83a4a2e8650628be1237cb5 (diff) | |
| parent | 689dfa894c57842a05bf6dc9f97e6bb71ec5f386 (diff) | |
Merge branch 'merge' into next
Merge "merge" branch to bring in various bug fixes that are
going into 3.8
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(); |