Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753108Ab1EPSRu (ORCPT ); Mon, 16 May 2011 14:17:50 -0400 Received: from mail-bw0-f52.google.com ([209.85.214.52]:60031 "EHLO mail-bw0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753020Ab1EPSRr (ORCPT ); Mon, 16 May 2011 14:17:47 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:from:to:cc:subject:date:message-id:x-mailer:in-reply-to :references; b=dcw7m/Wo6V1peFJlKvsCFuOmsr2zwPfpsY8RLZkX/CmdG0Uu0bD10THGR3MSHXJ98Y sMETlilo1LUU8T8MdpdOGbmL7U03yQxEoDLLA74N38cEK+39TKyJIhhs81mYncB/g8yZ CVnrAOdGAvG0cRGXBcUoX4a0Xv+WttByc/BXg= From: Tejun Heo To: oleg@redhat.com, jan.kratochvil@redhat.com, vda.linux@googlemail.com Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, indan@nul.nu, bdonlan@gmail.com, Tejun Heo Subject: [PATCH 09/10] ptrace: add JOBCTL_BLOCK_NOTIFY Date: Mon, 16 May 2011 20:17:28 +0200 Message-Id: <1305569849-10448-10-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1305569849-10448-1-git-send-email-tj@kernel.org> References: <1305569849-10448-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4428 Lines: 133 For to-be-added notification retraps, other tasks need to be able to tell whether ptrace request is currently in progress while tracee is in STOP trap. This patch adds JOBCTL_BLOCK_NOTIFY which is set on ptrace_check_attach() if the request requires tracee to be trapped and it's trapped for STOP, and cleared when ptrace syscall finishes. This flag isn't used yet. Signed-off-by: Tejun Heo --- include/linux/ptrace.h | 2 + include/linux/sched.h | 1 + kernel/ptrace.c | 51 ++++++++++++++++++++++++++++++++++++++++++++--- 3 files changed, 50 insertions(+), 4 deletions(-) diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 72b9150..b0c1347 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -73,6 +73,8 @@ #define PTRACE_EVENT_EXIT 6 #define PTRACE_EVENT_STOP 7 +#define PTRACE_STOP_SI_CODE (__SI_TRAP | SIGTRAP | PTRACE_EVENT_STOP << 8) + /* flags in siginfo.si_pt_flags from PTRACE_GETSIGINFO */ #define PTRACE_SI_STOPPED 0x00000001 /* tracee is job control stopped */ diff --git a/include/linux/sched.h b/include/linux/sched.h index d8a11cb..1f082d9 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1786,6 +1786,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * #define JOBCTL_STOP_CONSUME (1 << 18) /* consume group stop count */ #define JOBCTL_TRAP_STOP (1 << 19) /* trap for STOP */ #define JOBCTL_TRAPPING (1 << 21) /* switching to TRACED */ +#define JOBCTL_BLOCK_NOTIFY (1 << 22) /* block NOTIFY re-traps */ #define JOBCTL_TRAP_MASK JOBCTL_TRAP_STOP #define JOBCTL_PENDING_MASK (JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index c12daec..d382f81 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -189,10 +189,24 @@ int ptrace_check_attach(struct task_struct *child, bool ignore_state) */ spin_lock_irq(&child->sighand->siglock); WARN_ON_ONCE(task_is_stopped(child)); - if (task_is_traced(child) || ignore_state) + + if (ignore_state) { + ret = 0; + } else if (task_is_traced(child)) { + siginfo_t *si = child->last_siginfo; + + /* + * If STOP trapped, ptrace notification may cause + * re-traps, which we don't want while ptrace + * request is in progress. Block notification. + */ + if (si && si->si_code == PTRACE_STOP_SI_CODE) + child->jobctl |= JOBCTL_BLOCK_NOTIFY; ret = 0; - else if (ptrace_wait_trapping(child)) + } else if (ptrace_wait_trapping(child)) { return restart_syscall(); + } + spin_unlock_irq(&child->sighand->siglock); } read_unlock(&tasklist_lock); @@ -889,6 +903,35 @@ static struct task_struct *ptrace_get_task_struct(pid_t pid) #define arch_ptrace_attach(child) do { } while (0) #endif +/** + * ptrace_put_task_struct - ptrace request processing done, put child + * @child: child task struct to put + * + * ptrace request processing for @child is finished. Clean up and put + * @child. This function clears %JOBCTL_BLOCK_NOTIFY which can be set by + * ptrace_check_attach(). + */ +static void ptrace_put_task_struct(struct task_struct *child) +{ + unsigned long flags; + + if (!(child->jobctl & JOBCTL_BLOCK_NOTIFY)) + goto out_put; + + if (unlikely(!lock_task_sighand(child, &flags))) + goto out_put; + + /* + * Make sure @chlid is still ptraced by us and clear BLOCK_NOTIFY. + */ + if (likely((child->ptrace & PT_PTRACED) && child->parent == current)) + child->jobctl &= ~JOBCTL_BLOCK_NOTIFY; + + unlock_task_sighand(child, &flags); +out_put: + put_task_struct(child); +} + SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, unsigned long, data) { @@ -927,7 +970,7 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, ret = arch_ptrace(child, request, addr, data); out_put_task_struct: - put_task_struct(child); + ptrace_put_task_struct(child); out: return ret; } @@ -1068,7 +1111,7 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, ret = compat_arch_ptrace(child, request, addr, data); out_put_task_struct: - put_task_struct(child); + ptrace_put_task_struct(child); out: return ret; } -- 1.7.1 -- 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/