linux-kernel - Re: [PATCH v4 3.0-rc2-tip 3/22] 3: uprobes: Adding and remove a uprobe in a rb tree.

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Message-ID: <20110608102957.GA10529@linux.vnet.ibm.com>
Date:	Wed, 8 Jun 2011 15:59:57 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Josh Stone <jistone@...hat.com>
Cc:	Stephen Wilson <wilsons@...rt.ca>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>,
	Linux-mm <linux-mm@...ck.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jonathan Corbet <corbet@....net>,
	Hugh Dickins <hughd@...gle.com>,
	Christoph Hellwig <hch@...radead.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Roland McGrath <roland@...k.frob.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4 3.0-rc2-tip 3/22]  3: uprobes: Adding and remove a
 uprobe in a rb tree.

* Josh Stone <jistone@...hat.com> [2011-06-08 00:04:39]:

> On 06/07/2011 09:12 PM, Stephen Wilson wrote:
> > Also, changing the argument order seems to solve the issue reported by
> > Josh Stone where only the uprobe with the lowest address was responding
> > (thou I did not test with perf, just lightly with the trace_event
> > interface).
> 
> Makes sense, and indeed after swapping the arguments to both calls, the
> perf test I gave now works as expected.  Thanks!
> 
> Josh

Thanks Stephen for the fix and Josh for both reporting and confirming
that the fix works. 

Stephen, Along with the parameter interchange, I also modified the
parameter name so that they dont confuse with the argument names in
match_uprobe.  Otherwise 'r' in __find_uprobe would correspond to 'l' in 
match_uprobe. The result is something like below.

I am resending the faulty patch with the fix and also checked in the fix
into my git tree.

-- 
Thanks and Regards
Srikar

diff --git a/kernel/uprobes.c b/kernel/uprobes.c
index 95c16dd..72f21db 100644
--- a/kernel/uprobes.c
+++ b/kernel/uprobes.c
@@ -363,14 +363,14 @@ static int match_uprobe(struct uprobe *l, struct uprobe *r, int *match_inode)
 static struct uprobe *__find_uprobe(struct inode * inode,
 			 loff_t offset, struct rb_node **close_match)
 {
-	struct uprobe r = { .inode = inode, .offset = offset };
+	struct uprobe u = { .inode = inode, .offset = offset };
 	struct rb_node *n = uprobes_tree.rb_node;
 	struct uprobe *uprobe;
 	int match, match_inode;
 
 	while (n) {
 		uprobe = rb_entry(n, struct uprobe, rb_node);
-		match = match_uprobe(uprobe, &r, &match_inode);
+		match = match_uprobe(&u, uprobe, &match_inode);
 		if (close_match && match_inode)
 			*close_match = n;
 
@@ -412,7 +412,7 @@ static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
 	while (*p) {
 		parent = *p;
 		u = rb_entry(parent, struct uprobe, rb_node);
-		match = match_uprobe(u, uprobe, NULL);
+		match = match_uprobe(uprobe, u, NULL);
 		if (!match) {
 			atomic_inc(&u->ref);
 			return u;
--
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