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| author | Olof Johansson <olof@lixom.net> | 2013-01-27 22:07:11 -0800 |
|---|---|---|
| committer | Olof Johansson <olof@lixom.net> | 2013-01-27 22:07:20 -0800 |
| commit | 6b914c998787d65022e80d6262dfd0edef58cadb (patch) | |
| tree | ec9d9605ae08e6e40664c4302a181979ab4fe1d3 /arch/x86/kernel/step.c | |
| parent | 1f87a404d02a96519284e1928445ca5cfe9667db (diff) | |
| parent | 949db153b6466c6f7cad5a427ecea94985927311 (diff) | |
| download | linux-6b914c998787d65022e80d6262dfd0edef58cadb.tar.bz2 | |
Merge tag 'v3.8-rc5' into next/cleanup
Linux 3.8-rc5
Signed-off-by: Olof Johansson <olof@lixom.net>
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 cd3b2438a980..9b4d51d0c0d0 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(); |