linux-kernel - [PATCH v4 1/3] stacktrace: Remove weak version of save_stack_trace_tsk

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Date:   Tue, 11 Jun 2019 16:13:18 +0200
From:   Miroslav Benes <mbenes@...e.cz>
To:     jpoimboe@...hat.com, jikos@...nel.org, pmladek@...e.com
Cc:     joe.lawrence@...hat.com, kamalesh@...ux.vnet.ibm.com,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        Miroslav Benes <mbenes@...e.cz>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH v4 1/3] stacktrace: Remove weak version of save_stack_trace_tsk_reliable()

Recent rework of stack trace infrastructure introduced a new set of
helpers for common stack trace operations (commit e9b98e162aa5
("stacktrace: Provide helpers for common stack trace operations") and
related). As a result, save_stack_trace_tsk_reliable() is not directly
called anywhere. Livepatch, currently the only user of the reliable
stack trace feature, now calls stack_trace_save_tsk_reliable().

When CONFIG_HAVE_RELIABLE_STACKTRACE is set and depending on
CONFIG_ARCH_STACKWALK, stack_trace_save_tsk_reliable() calls either
arch_stack_walk_reliable() or mentioned save_stack_trace_tsk_reliable().
x86_64 defines the former, ppc64le the latter. All other architectures
do not have HAVE_RELIABLE_STACKTRACE and include/linux/stacktrace.h
defines -ENOSYS returning version for them.

In short, stack_trace_save_tsk_reliable() returning -ENOSYS defined in
include/linux/stacktrace.h serves the same purpose as the old weak
version of save_stack_trace_tsk_reliable() which is therefore no longer
needed.

Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Miroslav Benes <mbenes@...e.cz>
---
 kernel/stacktrace.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index 36139de0a3c4..0c3f00db9069 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -255,14 +255,6 @@ save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 	WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
 }

-__weak int
-save_stack_trace_tsk_reliable(struct task_struct *tsk,
-			      struct stack_trace *trace)
-{
-	WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n");
-	return -ENOSYS;
-}
-
 /**
  * stack_trace_save - Save a stack trace into a storage array
  * @store:	Pointer to storage array
-- 
2.21.0