From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by ozlabs.org (Postfix) with ESMTP id C3F122C0099 for ; Thu, 27 Jun 2013 00:24:00 +1000 (EST) Date: Wed, 26 Jun 2013 16:19:16 +0200 From: Oleg Nesterov To: Benjamin Herrenschmidt Subject: Re: linux-next: manual merge of the akpm tree with the powerpc tree Message-ID: <20130626141916.GA30716@redhat.com> References: <20130626165642.8740ecb6d5d5882b06f173c8@canb.auug.org.au> <1372234231.18612.6.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1372234231.18612.6.camel@pasglop> Cc: Stephen Rothwell , Michael Neuling , linux-kernel@vger.kernel.org, linux-next@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 06/26, Benjamin Herrenschmidt wrote: > > On Wed, 2013-06-26 at 16:56 +1000, Stephen Rothwell wrote: > > Today's linux-next merge of the akpm tree got a conflict in > > arch/powerpc/kernel/ptrace.c between commit b0b0aa9c7faf > > ("powerpc/hw_brk: Fix setting of length for exact mode breakpoints") from > > the powerpc tree and commit "ptrace/powerpc: revert "hw_breakpoints: Fix > > racy access to ptrace breakpoints"" from the akpm tree. > > > > I fixed it up (see below) and can carry the fix as necessary (no action > > is required). > > Where does the latter come from ? ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch attached below. You were cc'ed every time ;) > Why didn't it go through the powerpc tree ? Because this series needs to update any user of ptrace_get/put_breakpoints in arch/ (simply remove these calls), then change the core kernel code, then fix arch/86. ------------------------------------------------------ From: Oleg Nesterov Subject: ptrace/powerpc: revert "hw_breakpoints: Fix racy access to ptrace breakpoints" This reverts commit 07fa7a0a8a586 ("hw_breakpoints: Fix racy access to ptrace breakpoints") and removes ptrace_get/put_breakpoints() added by other commits. 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. Signed-off-by: Oleg Nesterov Acked-by: Michael Neuling Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jan Kratochvil Cc: Paul Mundt Cc: Will Deacon Cc: Prasad Cc: Russell King Signed-off-by: Andrew Morton --- arch/powerpc/kernel/ptrace.c | 20 -------------------- 1 file changed, 20 deletions(-) diff -puN arch/powerpc/kernel/ptrace.c~ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints arch/powerpc/kernel/ptrace.c --- a/arch/powerpc/kernel/ptrace.c~ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints +++ a/arch/powerpc/kernel/ptrace.c @@ -974,16 +974,12 @@ int ptrace_set_debugreg(struct task_stru hw_brk.type = (data & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL; hw_brk.len = 8; #ifdef CONFIG_HAVE_HW_BREAKPOINT - if (ptrace_get_breakpoints(task) < 0) - return -ESRCH; - bp = thread->ptrace_bps[0]; if ((!data) || !(hw_brk.type & HW_BRK_TYPE_RDWR)) { if (bp) { unregister_hw_breakpoint(bp); thread->ptrace_bps[0] = NULL; } - ptrace_put_breakpoints(task); return 0; } if (bp) { @@ -996,11 +992,9 @@ int ptrace_set_debugreg(struct task_stru ret = modify_user_hw_breakpoint(bp, &attr); if (ret) { - ptrace_put_breakpoints(task); return ret; } thread->ptrace_bps[0] = bp; - ptrace_put_breakpoints(task); thread->hw_brk = hw_brk; return 0; } @@ -1015,12 +1009,9 @@ int ptrace_set_debugreg(struct task_stru ptrace_triggered, NULL, task); if (IS_ERR(bp)) { thread->ptrace_bps[0] = NULL; - ptrace_put_breakpoints(task); return PTR_ERR(bp); } - ptrace_put_breakpoints(task); - #endif /* CONFIG_HAVE_HW_BREAKPOINT */ task->thread.hw_brk = hw_brk; #else /* CONFIG_PPC_ADV_DEBUG_REGS */ @@ -1439,9 +1430,6 @@ static long ppc_set_hwdebug(struct task_ if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE) brk.type |= HW_BRK_TYPE_WRITE; #ifdef CONFIG_HAVE_HW_BREAKPOINT - if (ptrace_get_breakpoints(child) < 0) - return -ESRCH; - /* * Check if the request is for 'range' breakpoints. We can * support it if range < 8 bytes. @@ -1449,12 +1437,10 @@ static long ppc_set_hwdebug(struct task_ if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE) { len = bp_info->addr2 - bp_info->addr; } else if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT) { - ptrace_put_breakpoints(child); return -EINVAL; } bp = thread->ptrace_bps[0]; if (bp) { - ptrace_put_breakpoints(child); return -ENOSPC; } @@ -1468,11 +1454,9 @@ static long ppc_set_hwdebug(struct task_ ptrace_triggered, NULL, child); if (IS_ERR(bp)) { thread->ptrace_bps[0] = NULL; - ptrace_put_breakpoints(child); return PTR_ERR(bp); } - ptrace_put_breakpoints(child); return 1; #endif /* CONFIG_HAVE_HW_BREAKPOINT */ @@ -1516,16 +1500,12 @@ static long ppc_del_hwdebug(struct task_ return -EINVAL; #ifdef CONFIG_HAVE_HW_BREAKPOINT - if (ptrace_get_breakpoints(child) < 0) - return -ESRCH; - bp = thread->ptrace_bps[0]; if (bp) { unregister_hw_breakpoint(bp); thread->ptrace_bps[0] = NULL; } else ret = -ENOENT; - ptrace_put_breakpoints(child); return ret; #else /* CONFIG_HAVE_HW_BREAKPOINT */ if (child->thread.hw_brk.address == 0) _ Patches currently in -mm which might be from oleg@redhat.com are posix_cpu_timer-consolidate-expiry-time-type.patch posix_cpu_timers-consolidate-timer-list-cleanups.patch posix_cpu_timers-consolidate-expired-timers-check.patch posix-timers-correctly-get-dying-task-time-sample-in-posix_cpu_timer_schedule.patch posix_timers-fix-racy-timer-delta-caching-on-task-exit.patch lockdep-introduce-lock_acquire_exclusive-shared-helper-macros.patch lglock-update-lockdep-annotations-to-report-recursive-local-locks.patch autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch ptrace-arm-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch ptrace-sh-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints.patch ptrace-x86-simplify-the-disable-logic-in-ptrace_write_dr7.patch ptrace-x86-dont-delay-disable-till-second-pass-in-ptrace_write_dr7.patch ptrace-x86-introduce-ptrace_register_breakpoint.patch ptrace-x86-ptrace_write_dr7-should-create-bp-if-disabled.patch ptrace-x86-cleanup-ptrace_set_debugreg.patch ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild.patch ptrace-x86-flush_ptrace_hw_breakpoint-shoule-clear-the-virtual-debug-registers.patch x86-kill-tif_debug.patch