It isn't possible to get the stack of a running task (other than current) because we don't have the stack pointer and the stack can be inconsistent anyway. Add a safe stack saving facility which only saves the stack of the task if it's sleeping or if it's the current task.
Suggested-by: Jiri Kosina <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> --- include/linux/stacktrace.h | 2 ++ kernel/stacktrace.c | 22 ++++++++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h index 669045a..898f0fc 100644 --- a/include/linux/stacktrace.h +++ b/include/linux/stacktrace.h @@ -20,6 +20,8 @@ extern void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace); extern void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace); +extern void save_stack_trace_tsk_safe(struct task_struct *tsk, + struct stack_trace *trace); extern void print_stack_trace(struct stack_trace *trace, int spaces); extern int snprint_stack_trace(char *buf, size_t size, diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c index b6e4c16..49cdd7f 100644 --- a/kernel/stacktrace.c +++ b/kernel/stacktrace.c @@ -57,6 +57,28 @@ int snprint_stack_trace(char *buf, size_t size, } EXPORT_SYMBOL_GPL(snprint_stack_trace); +static void __save_stack_trace_tsk_safe(struct task_struct *tsk, + void *data) +{ + struct stack_trace *trace = data; + + if (tsk != current && tsk->on_cpu) + return; + + save_stack_trace_tsk(tsk, trace); +} + +/* + * If the task is sleeping, safely get its stack. Otherwise, do nothing, since + * the stack of a running task is undefined. + */ +void save_stack_trace_tsk_safe(struct task_struct *tsk, + struct stack_trace *trace) +{ + sched_task_call(__save_stack_trace_tsk_safe, tsk, trace); +} +EXPORT_SYMBOL_GPL(save_stack_trace_tsk_safe); + /* * Architectures that do not implement save_stack_trace_tsk or * save_stack_trace_regs get this weak alias and a once-per-bootup warning -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
