Date: Mon, 12 Mar 2012 12:53:28 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r232864 - in stable/9/sys: kern sys Message-ID: <201203121253.q2CCrS8e062624@svn.freebsd.org>
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Author: kib Date: Mon Mar 12 12:53:27 2012 New Revision: 232864 URL: http://svn.freebsd.org/changeset/base/232864 Log: MFC r232240: Currently, the debugger attached to the process executing vfork() does not get syscall exit notification until the child performed exec of exit. Swap the order of doing ptracestop() and waiting for P_PPWAIT clearing, by postponing the wait into syscallret after ptracestop() notification is done. Modified: stable/9/sys/kern/kern_fork.c stable/9/sys/kern/subr_syscall.c stable/9/sys/sys/proc.h Directory Properties: stable/9/sys/ (props changed) Modified: stable/9/sys/kern/kern_fork.c ============================================================================== --- stable/9/sys/kern/kern_fork.c Mon Mar 12 12:29:31 2012 (r232863) +++ stable/9/sys/kern/kern_fork.c Mon Mar 12 12:53:27 2012 (r232864) @@ -708,6 +708,10 @@ do_fork(struct thread *td, int flags, st _PHOLD(p2); p2_held = 1; } + if (flags & RFPPWAIT) { + td->td_pflags |= TDP_RFPPWAIT; + td->td_rfppwait_p = p2; + } PROC_UNLOCK(p2); if ((flags & RFSTOPPED) == 0) { /* @@ -740,14 +744,6 @@ do_fork(struct thread *td, int flags, st cv_wait(&p2->p_dbgwait, &p2->p_mtx); if (p2_held) _PRELE(p2); - - /* - * Preserve synchronization semantics of vfork. If waiting for - * child to exec or exit, set P_PPWAIT on child, and sleep on our - * proc (in case of exit). - */ - while (p2->p_flag & P_PPWAIT) - cv_wait(&p2->p_pwait, &p2->p_mtx); PROC_UNLOCK(p2); } Modified: stable/9/sys/kern/subr_syscall.c ============================================================================== --- stable/9/sys/kern/subr_syscall.c Mon Mar 12 12:29:31 2012 (r232863) +++ stable/9/sys/kern/subr_syscall.c Mon Mar 12 12:53:27 2012 (r232864) @@ -165,7 +165,7 @@ syscallenter(struct thread *td, struct s static inline void syscallret(struct thread *td, int error, struct syscall_args *sa __unused) { - struct proc *p; + struct proc *p, *p2; int traced; p = td->td_proc; @@ -223,4 +223,23 @@ syscallret(struct thread *td, int error, td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK); PROC_UNLOCK(p); } + + if (td->td_pflags & TDP_RFPPWAIT) { + /* + * Preserve synchronization semantics of vfork. If + * waiting for child to exec or exit, fork set + * P_PPWAIT on child, and there we sleep on our proc + * (in case of exit). + * + * Do it after the ptracestop() above is finished, to + * not block our debugger until child execs or exits + * to finish vfork wait. + */ + td->td_pflags &= ~TDP_RFPPWAIT; + p2 = td->td_rfppwait_p; + PROC_LOCK(p2); + while (p2->p_flag & P_PPWAIT) + cv_wait(&p2->p_pwait, &p2->p_mtx); + PROC_UNLOCK(p2); + } } Modified: stable/9/sys/sys/proc.h ============================================================================== --- stable/9/sys/sys/proc.h Mon Mar 12 12:29:31 2012 (r232863) +++ stable/9/sys/sys/proc.h Mon Mar 12 12:53:27 2012 (r232864) @@ -310,6 +310,7 @@ struct thread { struct vnet *td_vnet; /* (k) Effective vnet. */ const char *td_vnet_lpush; /* (k) Debugging vnet push / pop. */ struct trapframe *td_intr_frame;/* (k) Frame of the current irq */ + struct proc *td_rfppwait_p; /* (k) The vforked child */ }; struct mtx *thread_lock_block(struct thread *); @@ -414,6 +415,7 @@ do { \ #define TDP_CALLCHAIN 0x00400000 /* Capture thread's callchain */ #define TDP_IGNSUSP 0x00800000 /* Permission to ignore the MNTK_SUSPEND* */ #define TDP_AUDITREC 0x01000000 /* Audit record pending on thread */ +#define TDP_RFPPWAIT 0x02000000 /* Handle RFPPWAIT on syscall exit */ /* * Reasons that the current thread can not be run yet.
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