linux-kernel - [PATCH 2/5] uprobes: Do not setup ->active

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Message-ID: <20120914171554.GA29639@redhat.com>
Date:	Fri, 14 Sep 2012 19:15:54 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] uprobes: Do not setup ->active_uprobe/state prematurely

handle_swbp() sets utask->active_uprobe before handler_chain(),
and UTASK_SSTEP before pre_ssout(). This complicates the code
for no reason,  arch_ hooks or consumer->handler() should not
(and can't) use this info.

Change handle_swbp() to initialize them after pre_ssout(), and
remove the no longer needed cleanup-utask code.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c |    9 +++------
 1 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 760acc1..9893cba 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1496,22 +1496,19 @@ static void handle_swbp(struct pt_regs *regs)
 		if (!utask)
 			goto cleanup_ret;
 	}
-	utask->active_uprobe = uprobe;
+
 	handler_chain(uprobe, regs);
 	if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs))
 		goto cleanup_ret;
 
-	utask->state = UTASK_SSTEP;
 	if (!pre_ssout(uprobe, regs, bp_vaddr)) {
 		arch_uprobe_enable_step(&uprobe->arch);
+		utask->active_uprobe = uprobe;
+		utask->state = UTASK_SSTEP;
 		return;
 	}
 
 cleanup_ret:
-	if (utask) {
-		utask->active_uprobe = NULL;
-		utask->state = UTASK_RUNNING;
-	}
 	if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
 
 		/*
-- 
1.5.5.1

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