From 7eaf51a2e094229b75cc0c315f1cbbe2f3960058 Mon Sep 17 00:00:00 2001 From: Joe Lawrence Date: Fri, 17 May 2019 14:51:17 -0400 Subject: [PATCH] stacktrace: Unbreak stack_trace_save_tsk_reliable() Miroslav reported that the livepatch self-tests were failing, specifically a case in which the consistency model ensures that a current executing function is not allowed to be patched, "TEST: busy target module". Recent renovations of stack_trace_save_tsk_reliable() left it returning only an -ERRNO success indication in some configuration combinations: klp_check_stack() ret = stack_trace_save_tsk_reliable() #ifdef CONFIG_ARCH_STACKWALK && CONFIG_HAVE_RELIABLE_STACKTRACE stack_trace_save_tsk_reliable() ret = arch_stack_walk_reliable() return 0 return -EINVAL ... return ret; ... if (ret < 0) /* stack_trace_save_tsk_reliable error */ nr_entries = ret; << 0 Previously (and currently for !CONFIG_ARCH_STACKWALK && CONFIG_HAVE_RELIABLE_STACKTRACE) stack_trace_save_tsk_reliable() returned the number of entries that it consumed in the passed storage array. In the case of the above config and trace, be sure to return the stacktrace_cookie.len on stack_trace_save_tsk_reliable() success. Fixes: 25e39e32b0a3f ("livepatch: Simplify stack trace retrieval") Reported-by: Miroslav Benes Signed-off-by: Joe Lawrence Signed-off-by: Thomas Gleixner Reviewed-by: Kamalesh Babulal Acked-by: Josh Poimboeuf Cc: live-patching@vger.kernel.org Cc: jikos@kernel.org Cc: pmladek@suse.com Link: https://lkml.kernel.org/r/20190517185117.24642-1-joe.lawrence@redhat.com --- kernel/stacktrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c index 27bafc1e271e..90d3e0bf0302 100644 --- a/kernel/stacktrace.c +++ b/kernel/stacktrace.c @@ -206,7 +206,7 @@ int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store, ret = arch_stack_walk_reliable(consume_entry, &c, tsk); put_task_stack(tsk); - return ret; + return ret ? ret : c.len; } #endif