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| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-02-04 15:51:49 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-02-04 15:51:49 +0100 |
| commit | 2fb20e2e35cd1455d022ab7a553d7f1663ffbdeb (patch) | |
| tree | 4b3bb0f76c15264fe7d4cced91127f3d96ff31f5 /arch/x86/kernel/step.c | |
| parent | Merge branch 'for-rmk/virt/kvm/core' of git://git.kernel.org/pub/scm/linux/ke... (diff) | |
| parent | Merge branch 'clocks/broadcast-arm' of git://linux-arm.org/linux-mr into for-... (diff) | |
| download | linux-2fb20e2e35cd1455d022ab7a553d7f1663ffbdeb.tar.xz linux-2fb20e2e35cd1455d022ab7a553d7f1663ffbdeb.zip | |
Merge branch 'for-rmk/broadcast' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux into devel-stable
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(); |