mirrors/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2024-11-23 17:53:37 +08:00
Code Issues Actions Packages Projects Releases Wiki Activity

nptl: Move cancel state out of cancelhandling

Browse Source 
Now that thread cancellation state is not accessed concurrently anymore,
it is possible to move it out the 'cancelhandling'.

The code is also simplified: CANCELLATION_P is replaced with a
internal pthread_testcancel call and the CANCELSTATE_BIT{MASK} is
removed.

With this behavior pthread_setcancelstate does not require to act on
cancellation if cancel type is asynchronous (is already handled either
by pthread_setcanceltype or by the signal handler).

Checked on x86_64-linux-gnu and aarch64-linux-gnu.
This commit is contained in:
Adhemerval Zanella 2020-03-31 15:43:25 -03:00
parent 26cfbb7162
commit 2b51742531
14 changed files with 34 additions and 63 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
manual/pattern.texi
View File

@ -1820,7 +1820,6 @@ the beginning of the vector.
@c (disable cancellation around exec_comm; it may do_cancel the
@c second time, if async cancel is enabled)
@c THREAD_ATOMIC_CMPXCHG_VAL dup ok
@c CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS dup ok
@c do_cancel @ascuplugin @ascuheap @acsmem
@c THREAD_ATOMIC_BIT_SET dup ok
@c pthread_unwind @ascuplugin @ascuheap @acsmem

3
manual/process.texi
View File

@ -68,7 +68,7 @@ until the subprogram terminates before you can do anything else.
@c CLEANUP_HANDLER @ascuplugin @ascuheap @acsmem
@c libc_cleanup_region_start @ascuplugin @ascuheap @acsmem
@c pthread_cleanup_push_defer @ascuplugin @ascuheap @acsmem
@c CANCELLATION_P @ascuplugin @ascuheap @acsmem
@c __pthread_testcancel @ascuplugin @ascuheap @acsmem
@c CANCEL_ENABLED_AND_CANCELED ok
@c do_cancel @ascuplugin @ascuheap @acsmem
@c cancel_handler ok
@ -86,7 +86,6 @@ until the subprogram terminates before you can do anything else.
@c SINGLE_THREAD_P ok
@c LIBC_CANCEL_ASYNC @ascuplugin @ascuheap @acsmem
@c libc_enable_asynccancel @ascuplugin @ascuheap @acsmem
@c CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS dup ok
@c do_cancel dup @ascuplugin @ascuheap @acsmem
@c LIBC_CANCEL_RESET ok
@c libc_disable_asynccancel ok

1
nptl/allocatestack.c
View File

@ -160,6 +160,7 @@ get_cached_stack (size_t *sizep, void **memp)
/* Cancellation handling is back to the default. */
result->cancelhandling = 0;
result->cancelstate = PTHREAD_CANCEL_ENABLE;
result->cleanup = NULL;
result->setup_failed = 0;

3
nptl/cancellation.c
View File

@ -44,7 +44,8 @@ __pthread_enable_asynccancel (void)
oldval);
if (__glibc_likely (curval == oldval))
{
if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
if (self->cancelstate == PTHREAD_CANCEL_ENABLE
&& CANCEL_CANCELED_AND_ASYNCHRONOUS (newval))
{
THREAD_SETMEM (self, result, PTHREAD_CANCELED);
__do_cancel ();

2
nptl/cleanup_defer.c
View File

@ -92,7 +92,7 @@ ___pthread_unregister_cancel_restore (__pthread_unwind_buf_t *buf)
cancelhandling = curval;
}
CANCELLATION_P (self);
__pthread_testcancel ();
}
}
versioned_symbol (libc, ___pthread_unregister_cancel_restore,

14
nptl/descr.h
View File

@ -277,9 +277,6 @@ struct pthread
/* Flags determining processing of cancellation. */
int cancelhandling;
/* Bit set if cancellation is disabled. */
#define CANCELSTATE_BIT 0
#define CANCELSTATE_BITMASK (0x01 << CANCELSTATE_BIT)
/* Bit set if asynchronous cancellation mode is selected. */
#define CANCELTYPE_BIT 1
#define CANCELTYPE_BITMASK (0x01 << CANCELTYPE_BIT)
@ -298,11 +295,8 @@ struct pthread
/* Mask for the rest. Helps the compiler to optimize. */
#define CANCEL_RESTMASK 0xffffff80
#define CANCEL_ENABLED_AND_CANCELED(value) \
(((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK \
| CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
#define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
(((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK \
#define CANCEL_CANCELED_AND_ASYNCHRONOUS(value) \
(((value) & (CANCELTYPE_BITMASK | CANCELED_BITMASK \
| EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK)) \
== (CANCELTYPE_BITMASK | CANCELED_BITMASK))
@ -404,6 +398,10 @@ struct pthread
/* Indicates whether is a C11 thread created by thrd_creat. */
bool c11;
/* Thread cancel state (PTHREAD_CANCEL_ENABLE or
PTHREAD_CANCEL_DISABLE). */
unsigned char cancelstate;
/* Used on strsignal. */
struct tls_internal_t tls_state;

2
nptl/libc-cleanup.c
View File

@ -79,7 +79,7 @@ __libc_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer)
cancelhandling = curval;
}
CANCELLATION_P (self);
__pthread_testcancel ();
}
}
libc_hidden_def (__libc_cleanup_pop_restore)

12
nptl/pthreadP.h
View File

@ -245,18 +245,6 @@ libc_hidden_proto (__pthread_current_priority)
#define INVALID_TD_P(pd) __builtin_expect ((pd)->tid <= 0, 0)
#define INVALID_NOT_TERMINATED_TD_P(pd) __builtin_expect ((pd)->tid < 0, 0)
/* Cancellation test. */
#define CANCELLATION_P(self) \
do { \
int cancelhandling = THREAD_GETMEM (self, cancelhandling); \
if (CANCEL_ENABLED_AND_CANCELED (cancelhandling)) \
{ \
THREAD_SETMEM (self, result, PTHREAD_CANCELED); \
__do_cancel (); \
} \
} while (0)
extern void __pthread_unwind (__pthread_unwind_buf_t *__buf)
__cleanup_fct_attribute __attribute ((__noreturn__))
#if !defined SHARED && !IS_IN (libpthread)

2
nptl/pthread_cancel.c
View File

@ -45,7 +45,7 @@ sigcancel_handler (int sig, siginfo_t *si, void *ctx)
int ch = atomic_load_relaxed (&self->cancelhandling);
/* Cancelation not enabled, not cancelled, or already exitting. */
if ((ch & CANCELSTATE_BITMASK) != 0
if (self->cancelstate == PTHREAD_CANCEL_DISABLE
|| (ch & CANCELED_BITMASK) == 0
|| (ch & EXITING_BITMASK) != 0)
return;

5
nptl/pthread_join_common.c
View File

@ -59,7 +59,10 @@ __pthread_clockjoin_ex (pthread_t threadid, void **thread_return,
&& (pd->cancelhandling
& (CANCELED_BITMASK | EXITING_BITMASK
| TERMINATED_BITMASK)) == 0))
&& !CANCEL_ENABLED_AND_CANCELED (self->cancelhandling))
&& !(self->cancelstate == PTHREAD_CANCEL_ENABLE
&& (pd->cancelhandling & (CANCELED_BITMASK | EXITING_BITMASK
| TERMINATED_BITMASK))
== CANCELED_BITMASK))
/* This is a deadlock situation. The threads are waiting for each
other to finish. Note that this is a "may" error. To be 100%
sure we catch this error we would have to lock the data

36
nptl/pthread_setcancelstate.c
View File

@ -31,39 +31,9 @@ __pthread_setcancelstate (int state, int *oldstate)
self = THREAD_SELF;
int oldval = THREAD_GETMEM (self, cancelhandling);
while (1)
{
int newval = (state == PTHREAD_CANCEL_DISABLE
? oldval | CANCELSTATE_BITMASK
: oldval & ~CANCELSTATE_BITMASK);
/* Store the old value. */
if (oldstate != NULL)
*oldstate = ((oldval & CANCELSTATE_BITMASK)
? PTHREAD_CANCEL_DISABLE : PTHREAD_CANCEL_ENABLE);
/* Avoid doing unnecessary work. The atomic operation can
potentially be expensive if the memory has to be locked and
remote cache lines have to be invalidated. */
if (oldval == newval)
break;
/* Update the cancel handling word. This has to be done
atomically since other bits could be modified as well. */
int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
oldval);
if (__glibc_likely (curval == oldval))
{
if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
__do_cancel ();
break;
}
/* Prepare for the next round. */
oldval = curval;
}
if (oldstate != NULL)
*oldstate = self->cancelstate;
self->cancelstate = state;
return 0;
}

3
nptl/pthread_setcanceltype.c
View File

@ -53,7 +53,8 @@ __pthread_setcanceltype (int type, int *oldtype)
oldval);
if (__glibc_likely (curval == oldval))
{
if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
if (self->cancelstate == PTHREAD_CANCEL_ENABLE
&& CANCEL_CANCELED_AND_ASYNCHRONOUS (newval))
{
THREAD_SETMEM (self, result, PTHREAD_CANCELED);
__do_cancel ();

11
nptl/pthread_testcancel.c
View File

@ -23,7 +23,16 @@
void
___pthread_testcancel (void)
{
CANCELLATION_P (THREAD_SELF);
struct pthread *self = THREAD_SELF;
int cancelhandling = THREAD_GETMEM (self, cancelhandling);
if (self->cancelstate == PTHREAD_CANCEL_ENABLE
&& (cancelhandling & CANCELED_BITMASK)
&& !(cancelhandling & EXITING_BITMASK)
&& !(cancelhandling & TERMINATED_BITMASK))
{
THREAD_SETMEM (self, result, PTHREAD_CANCELED);
__do_cancel ();
}
}
versioned_symbol (libc, ___pthread_testcancel, pthread_testcancel, GLIBC_2_34);
versioned_symbol (libc, ___pthread_testcancel, __pthread_testcancel,

2
sysdeps/nptl/dl-tls_init_tp.c
View File

@ -94,4 +94,6 @@ __tls_init_tp (void)
It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
purposes this is good enough. */
THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
THREAD_SETMEM (pd, cancelstate, PTHREAD_CANCEL_ENABLE);
}