linux-kernel - [PATCH v2 3/6] x86/stacktrace: remove STACKTRACE_DUMP_ONCE from __save_stack_trace

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Message-Id: <20180514140653.23678-3-jslaby@suse.cz>
Date:   Mon, 14 May 2018 16:06:50 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     mingo@...hat.com
Cc:     linux-kernel@...r.kernel.org, Jiri Slaby <jslaby@...e.cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH v2 3/6] x86/stacktrace: remove STACKTRACE_DUMP_ONCE from __save_stack_trace_reliable

The stack unwinding can sometimes fail yet. Especially with the
generated debug info. So do not yell at users -- live patching (the only
user of this interface) will inform the user about the failure
gracefully.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/kernel/stacktrace.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 3a4602c2324f..e0169b128523 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -125,20 +125,16 @@ __save_stack_trace_reliable(struct stack_trace *trace,
 		 * generated code which __kernel_text_address() doesn't know
 		 * about.
 		 */
-		if (!addr) {
-			STACKTRACE_DUMP_ONCE(task);
+		if (!addr)
 			return -EINVAL;
-		}
 
 		if (save_stack_address(trace, addr, false))
 			return -EINVAL;
 	}
 
 	/* Check for stack corruption */
-	if (unwind_error(&state)) {
-		STACKTRACE_DUMP_ONCE(task);
+	if (unwind_error(&state))
 		return -EINVAL;
-	}
 
 	/* Success path for non-user tasks, i.e. kthreads and idle tasks */
 	if (!(task->flags & (PF_KTHREAD | PF_IDLE)))
-- 
2.16.3