diff options
| author | Jens Axboe <axboe@kernel.dk> | 2013-02-20 08:26:06 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2013-02-20 08:26:06 +0100 |
| commit | d4308febf3551d46884561b7c3fdd62ad3ca7ff2 (patch) | |
| tree | b8c48122df7c36761c6fb5d70647a09605892b9f /arch/x86/kernel/step.c | |
| parent | c206c70924737db6836382c09ad2dacd04bb6204 (diff) | |
| parent | 087ffecdaa1875cc683a7a5bc0695b3ebfce3bad (diff) | |
Merge branch 'stable/for-jens-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-3.9/drivers
Konrad writes:
Please git pull the following branch:
git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/for-jens-3.9
which has bug-fixes that did not make it in v3.8. They all are marked as
material for the stable tree as well. There are two bug-fixes for
the code that has been in there for some time (that is the Jan's fix
and one of mine). And there are two bug-fixes for the persistent grant
feature that debuted in v3.8 for xen blk[back|front]end.
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(); |