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Pull the PT_ATTACH case out of the 'sendsig:' block.

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Most of the conditionals in the 'sendsig:' block are now only different
for PT_ATTACH vs other continue requests.  Pull the PT_ATTACH-specific
logic up into the PT_ATTACH case and simplify the 'sendsig:' block.  This
also permits moving the unlock of proctree_lock above the sendsig: label
since PT_KILL doesn't hold the lock and and the other cases all fall
through to the label.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D13073
This commit is contained in:
John Baldwin 2017-11-13 21:09:08 +00:00
parent d7a699d3d8
commit 2a2b23cae2
1 changed files with 47 additions and 49 deletions
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96
sys/kern/sys_process.c
View File

@ -920,10 +920,27 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
if (p->p_pptr != td->td_proc) {
proc_reparent(p, td->td_proc);
}
data = SIGSTOP;
CTR2(KTR_PTRACE, "PT_ATTACH: pid %d, oppid %d", p->p_pid,
p->p_oppid);
goto sendsig; /* in PT_CONTINUE below */
sx_xunlock(&proctree_lock);
proctree_locked = 0;
MPASS(p->p_xthread == NULL);
MPASS((p->p_flag & P_STOPPED_TRACE) == 0);
/*
* If already stopped due to a stop signal, clear the
* existing stop before triggering a traced SIGSTOP.
*/
if ((p->p_flag & P_STOPPED_SIG) != 0) {
PROC_SLOCK(p);
p->p_flag &= ~(P_STOPPED_SIG | P_WAITED);
thread_unsuspend(p);
PROC_SUNLOCK(p);
}
kern_psignal(p, SIGSTOP);
break;
case PT_CLEARSTEP:
CTR2(KTR_PTRACE, "PT_CLEARSTEP: tid %d (pid %d)", td2->td_tid,
@ -1123,12 +1140,11 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
break;
}
sx_xunlock(&proctree_lock);
proctree_locked = 0;
sendsig:
/* proctree_locked is true for all but PT_KILL. */
if (proctree_locked) {
sx_xunlock(&proctree_lock);
proctree_locked = 0;
}
MPASS(proctree_locked == 0);
/*
* Clear the pending event for the thread that just
@ -1138,54 +1154,36 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
*
* Deliver any pending signal via the reporting thread.
*/
if ((p->p_flag & P_STOPPED_TRACE) != 0) {
MPASS(p->p_xthread != NULL);
p->p_xthread->td_dbgflags &= ~TDB_XSIG;
p->p_xthread->td_xsig = data;
p->p_xthread = NULL;
p->p_xsig = data;
} else {
MPASS(p->p_xthread == NULL);
MPASS(req == PT_ATTACH);
}
MPASS(p->p_xthread != NULL);
p->p_xthread->td_dbgflags &= ~TDB_XSIG;
p->p_xthread->td_xsig = data;
p->p_xthread = NULL;
p->p_xsig = data;
if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) != 0) {
/*
* P_WKILLED is insurance that a PT_KILL/SIGKILL always
* works immediately, even if another thread is
* unsuspended first and attempts to handle a different
* signal or if the POSIX.1b style signal queue cannot
* accommodate any new signals.
*/
if (data == SIGKILL)
p->p_flag |= P_WKILLED;
/*
* P_WKILLED is insurance that a PT_KILL/SIGKILL
* always works immediately, even if another thread is
* unsuspended first and attempts to handle a
* different signal or if the POSIX.1b style signal
* queue cannot accommodate any new signals.
*/
if (data == SIGKILL)
p->p_flag |= P_WKILLED;
if (req == PT_DETACH) {
FOREACH_THREAD_IN_PROC(p, td3)
td3->td_dbgflags &= ~TDB_SUSPEND;
}
/*
* Unsuspend all threads. To leave a thread
* suspended, use PT_SUSPEND to suspend it
* before continuing the process.
*/
PROC_SLOCK(p);
p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG|P_WAITED);
thread_unsuspend(p);
PROC_SUNLOCK(p);
if (req == PT_DETACH) {
FOREACH_THREAD_IN_PROC(p, td3)
td3->td_dbgflags &= ~TDB_SUSPEND;
}
/*
* For requests other than PT_ATTACH, P_STOPPED_TRACE
* was set, so any pending signal in 'data' is
* delivered via the reporting thread (p_xthread).
* For PT_ATTACH the process is not yet stopped for
* tracing, so P_STOPPED_TRACE cannot be set and the
* SIGSTOP must be delivered to the process.
* Unsuspend all threads. To leave a thread
* suspended, use PT_SUSPEND to suspend it before
* continuing the process.
*/
if (req == PT_ATTACH)
kern_psignal(p, data);
PROC_SLOCK(p);
p->p_flag &= ~(P_STOPPED_TRACE | P_STOPPED_SIG | P_WAITED);
thread_unsuspend(p);
PROC_SUNLOCK(p);
break;
case PT_WRITE_I: