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Hurd: make sigstates hold a reference on thread ports

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This change is required in order to correctly release per-thread
resources. Directly reusing the threading library reference isn't
possible since the sigstate is also used early in the main thread,
before threading is initialized.

* hurd/hurd/signal.h (_hurd_self_sigstate): Drop thread reference after
calling _hurd_thread_sigstate.
(_hurd_critical_section_lock): Likewise.
* hurd/hurdsig.c (_hurd_thread_sigstate): Add a reference on the thread.
(_hurd_sigstate_delete): Drop thread reference.
This commit is contained in:
Richard Braun 2020-12-21 02:10:16 +01:00 committed by Samuel Thibault
parent 53432762ac
commit 5c06743c8a
2 changed files with 29 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

19
hurd/hurd/signal.h
View file

@ -67,7 +67,9 @@ struct hurd_sigstate
spin_lock_t lock; /* Locks most of the rest of the structure. */
/* The signal state holds a reference on the thread port. */
thread_t thread;
struct hurd_sigstate *next; /* Linked-list of thread sigstates. */
sigset_t blocked; /* What signals are blocked. */
@ -119,7 +121,9 @@ struct hurd_sigstate
extern struct hurd_sigstate *_hurd_sigstates;
/* Get the sigstate of a given thread, taking its lock. */
/* Get the sigstate of a given thread. If there was no sigstate for
the thread, one is created, and the thread gains a reference. If
the given thread is MACH_PORT_NULL, return the global sigstate. */
extern struct hurd_sigstate *_hurd_thread_sigstate (thread_t);
@ -162,7 +166,11 @@ _HURD_SIGNAL_H_EXTERN_INLINE struct hurd_sigstate *
_hurd_self_sigstate (void)
{
if (THREAD_GETMEM (THREAD_SELF, _hurd_sigstate) == NULL)
THREAD_SETMEM (THREAD_SELF, _hurd_sigstate, _hurd_thread_sigstate (__mach_thread_self ()));
{
thread_t self = __mach_thread_self ();
THREAD_SETMEM (THREAD_SELF, _hurd_sigstate, _hurd_thread_sigstate (self));
__mach_port_deallocate (__mach_task_self (), self);
}
return THREAD_GETMEM (THREAD_SELF, _hurd_sigstate);
}
# endif
@ -210,12 +218,15 @@ _hurd_critical_section_lock (void)
ss = THREAD_GETMEM (THREAD_SELF, _hurd_sigstate);
if (ss == NULL)
{
thread_t self = __mach_thread_self ();
/* The thread variable is unset; this must be the first time we've
asked for it. In this case, the critical section flag cannot
possible already be set. Look up our sigstate structure the slow
way. */
ss = _hurd_thread_sigstate (__mach_thread_self ());
THREAD_SETMEM(THREAD_SELF, _hurd_sigstate, ss);
ss = _hurd_thread_sigstate (self);
THREAD_SETMEM (THREAD_SELF, _hurd_sigstate, ss);
__mach_port_deallocate (__mach_task_self (), self);
}
if (! __spin_try_lock (&ss->critical_section_lock))

17
hurd/hurdsig.c
View file

@ -114,6 +114,8 @@ _hurd_thread_sigstate (thread_t thread)
}
else
{
error_t err;
/* Use the global actions as a default for new threads. */
struct hurd_sigstate *s = _hurd_global_sigstate;
if (s)
@ -127,6 +129,11 @@ _hurd_thread_sigstate (thread_t thread)
ss->next = _hurd_sigstates;
_hurd_sigstates = ss;
err = __mach_port_mod_refs (__mach_task_self (), thread,
MACH_PORT_RIGHT_SEND, 1);
if (err)
__libc_fatal ("hurd: Can't add reference on Mach thread\n");
}
}
__mutex_unlock (&_hurd_siglock);
@ -135,8 +142,7 @@ _hurd_thread_sigstate (thread_t thread)
libc_hidden_def (_hurd_thread_sigstate)
/* Destroy a sigstate structure. Called by libpthread just before the
* corresponding thread is terminated (the kernel thread port must remain valid
* until this function is called.) */
* corresponding thread is terminated. */
void
_hurd_sigstate_delete (thread_t thread)
{
@ -153,7 +159,12 @@ _hurd_sigstate_delete (thread_t thread)
__mutex_unlock (&_hurd_siglock);
if (ss)
free (ss);
{
if (ss->thread != MACH_PORT_NULL)
__mach_port_deallocate (__mach_task_self (), ss->thread);
free (ss);
}
}
/* Make SS a global receiver, with pthread signal semantics. */