linux-kernel - [PATCH] x86/kgdb: return 0 from kgdb_arch_set

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Message-ID: <20190531194755.6320-1-mmullins@fb.com>
Date:   Fri, 31 May 2019 12:47:54 -0700
From:   Matt Mullins <mmullins@...com>
To:     <mmullins@...com>, <bp@...en8.de>, <mingo@...hat.com>,
        <luto@...nel.org>, <namit@...are.com>, <peterz@...radead.org>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, <x86@...nel.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        "Rick Edgecombe" <rick.p.edgecombe@...el.com>,
        Christophe Leroy <christophe.leroy@....fr>,
        Douglas Anderson <dianders@...omium.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86/kgdb: return 0 from kgdb_arch_set_breakpoint

err must be nonzero in order to reach text_poke(), which caused kgdb to
fail to set breakpoints:

	(gdb) break __x64_sys_sync
	Breakpoint 1 at 0xffffffff81288910: file ../fs/sync.c, line 124.
	(gdb) c
	Continuing.
	Warning:
	Cannot insert breakpoint 1.
	Cannot access memory at address 0xffffffff81288910

	Command aborted.

Fixes: 86a22057127d ("x86/kgdb: Avoid redundant comparison of patched code")
Signed-off-by: Matt Mullins <mmullins@...com>
---
 arch/x86/kernel/kgdb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 9a8c1648fc9a..6690c5652aeb 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -758,7 +758,7 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 		       BREAK_INSTR_SIZE);
 	bpt->type = BP_POKE_BREAKPOINT;
 
-	return err;
+	return 0;
 }
 
 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
-- 
2.17.1