Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752484Ab3DNQI0 (ORCPT ); Sun, 14 Apr 2013 12:08:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42623 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752347Ab3DNQIY (ORCPT ); Sun, 14 Apr 2013 12:08:24 -0400 Date: Sun, 14 Apr 2013 18:05:26 +0200 From: Oleg Nesterov To: Andrew Morton Cc: Benjamin Herrenschmidt , Frederic Weisbecker , Jan Kratochvil , Ingo Molnar , Paul Mackerras , Paul Mundt , Prasad , Russell King , Will Deacon , linux-kernel@vger.kernel.org Subject: [PATCH 1/5] ptrace/x86: Revert "hw_breakpoints: Fix racy access to ptrace breakpoints" Message-ID: <20130414160526.GA7635@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130414160501.GA7612@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2704 Lines: 100 This reverts commit 87dc669ba25777b67796d7262c569429e58b1ed4. The patch was fine but we can no longer race with SIGKILL after 9899d11f "ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL", the __TASK_TRACED tracee can't be woken up and ->ptrace_bps[] can't go away. The patch only removes ptrace_get_breakpoints/ptrace_put_breakpoints and does a couple of "while at it" cleanups, it doesn't remove other changes from the reverted commit. Signed-off-by: Oleg Nesterov --- arch/x86/kernel/ptrace.c | 28 +++++----------------------- 1 files changed, 5 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 29a8120..7a98b21 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -641,9 +641,6 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data) unsigned len, type; struct perf_event *bp; - if (ptrace_get_breakpoints(tsk) < 0) - return -ESRCH; - data &= ~DR_CONTROL_RESERVED; old_dr7 = ptrace_get_dr7(thread->ptrace_bps); restore: @@ -692,9 +689,7 @@ restore: goto restore; } - ptrace_put_breakpoints(tsk); - - return ((orig_ret < 0) ? orig_ret : rc); + return orig_ret < 0 ? orig_ret : rc; } /* @@ -706,18 +701,10 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n) unsigned long val = 0; if (n < HBP_NUM) { - struct perf_event *bp; + struct perf_event *bp = thread->ptrace_bps[n]; - if (ptrace_get_breakpoints(tsk) < 0) - return -ESRCH; - - bp = thread->ptrace_bps[n]; - if (!bp) - val = 0; - else + if (bp) val = bp->hw.info.address; - - ptrace_put_breakpoints(tsk); } else if (n == 6) { val = thread->debugreg6; } else if (n == 7) { @@ -734,9 +721,6 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr, struct perf_event_attr attr; int err = 0; - if (ptrace_get_breakpoints(tsk) < 0) - return -ESRCH; - if (!t->ptrace_bps[nr]) { ptrace_breakpoint_init(&attr); /* @@ -762,7 +746,7 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr, */ if (IS_ERR(bp)) { err = PTR_ERR(bp); - goto put; + goto out; } t->ptrace_bps[nr] = bp; @@ -773,9 +757,7 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr, attr.bp_addr = addr; err = modify_user_hw_breakpoint(bp, &attr); } - -put: - ptrace_put_breakpoints(tsk); +out: return err; } -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/