linux-kernel - [tip:perf/core] ksym_tracer: Fix breakpoint removal after modification

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Message-ID: <tip-d99be40aff88722ab03ee295e4f6c13a4cca9a3d@git.kernel.org>
Date:	Thu, 26 Nov 2009 08:44:42 GMT
From:	tip-bot for Frederic Weisbecker <fweisbec@...il.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	fweisbec@...il.com, rostedt@...dmis.org, tglx@...utronix.de,
	prasad@...ux.vnet.ibm.com, mingo@...e.hu
Subject: [tip:perf/core] ksym_tracer: Fix breakpoint removal after modification

Commit-ID:  d99be40aff88722ab03ee295e4f6c13a4cca9a3d
Gitweb:     http://git.kernel.org/tip/d99be40aff88722ab03ee295e4f6c13a4cca9a3d
Author:     Frederic Weisbecker <fweisbec@...il.com>
AuthorDate: Thu, 26 Nov 2009 05:35:40 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Thu, 26 Nov 2009 09:29:20 +0100

ksym_tracer: Fix breakpoint removal after modification

The error path of a breakpoint modification is broken in
the ksym tracer. A modified breakpoint hlist node is immediately
released after its removal. Also we leak a breakpoint in this
case.

Fix the path.

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Prasad <prasad@...ux.vnet.ibm.com>
LKML-Reference: <1259210142-5714-1-git-send-regression-fweisbec@...il.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 kernel/trace/trace_ksym.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 11935b5..9f040e4 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -339,14 +339,20 @@ static ssize_t ksym_trace_filter_write(struct file *file,
 					ksym_hbp_handler, true);
 			if (IS_ERR(entry->ksym_hbp))
 				entry->ksym_hbp = NULL;
-			if (!entry->ksym_hbp)
+
+			/* modified without problem */
+			if (entry->ksym_hbp) {
+				ret = 0;
 				goto out;
+			}
+		} else {
+			ret = 0;
 		}
+		/* Error or "symbol:---" case: drop it */
 		ksym_filter_entry_count--;
 		hlist_del_rcu(&(entry->ksym_hlist));
 		synchronize_rcu();
 		kfree(entry);
-		ret = 0;
 		goto out;
 	} else {
 		/* Check for malformed request: (4) */
--
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