From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 8 Jul 2013 23:00:51 +0000 (-0700)
Subject: ptrace/arm: revert "hw_breakpoints: Fix racy access to ptrace breakpoints"
X-Git-Tag: firefly_0821_release~176^2~5754^2~51
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=6af9df7f5ba35806a5919d3a36d95fd40e210b89;p=firefly-linux-kernel-4.4.55.git

ptrace/arm: revert "hw_breakpoints: Fix racy access to ptrace breakpoints"

This reverts commit bf0b8f4b55e5 ("hw_breakpoints: Fix racy access to
ptrace breakpoints").

The patch was fine but we can no longer race with SIGKILL after commit
9899d11f6544 ("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.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 2bc1514d6dbe..0dd3b79b15c3 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -886,20 +886,12 @@ long arch_ptrace(struct task_struct *child, long request,
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 		case PTRACE_GETHBPREGS:
-			if (ptrace_get_breakpoints(child) < 0)
-				return -ESRCH;
-
 			ret = ptrace_gethbpregs(child, addr,
 						(unsigned long __user *)data);
-			ptrace_put_breakpoints(child);
 			break;
 		case PTRACE_SETHBPREGS:
-			if (ptrace_get_breakpoints(child) < 0)
-				return -ESRCH;
-
 			ret = ptrace_sethbpregs(child, addr,
 						(unsigned long __user *)data);
-			ptrace_put_breakpoints(child);
 			break;
 #endif