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nptl: Implement raise in terms of pthread_kill

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Now that pthread_kill is provided by libc.so it is possible to
implement the generic POSIX implementation as
'pthread_kill(pthread_self(), sig)'.

For Linux implementation, pthread_kill read the targeting TID from
the TCB.  For raise, this it not possible because it would make raise
fail when issue after vfork (where creates the resulting process
has a different TID from the parent, but its TCB is not updated as
for pthread_create).  To make raise use pthread_kill, it is make
usable from vfork by getting the target thread id through gettid
syscall.

Checked on x86_64-linux-gnu and aarch64-linux-gnu.
This commit is contained in:
Adhemerval Zanella
2020-12-07 16:21:55 -03:00
parent 8c1c0aae20
commit f779b1efb3
8 changed files with 50 additions and 71 deletions
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42
nptl/pthread_kill.c
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@@ -28,24 +28,40 @@ __pthread_kill (pthread_t threadid, int signo)
if (__is_internal_signal (signo))
return EINVAL;
/* Force load of pd->tid into local variable or register. Otherwise
if a thread exits between ESRCH test and tgkill, we might return
EINVAL, because pd->tid would be cleared by the kernel. */
pid_t tid;
struct pthread *pd = (struct pthread *) threadid;
pid_t tid = atomic_forced_read (pd->tid);
if (__glibc_unlikely (tid <= 0))
/* Not a valid thread handle. */
return ESRCH;
/* We have a special syscall to do the work. */
pid_t pid = __getpid ();
if (pd == THREAD_SELF)
/* It is a special case to handle raise() implementation after a vfork
call (which does not update the PD tid field). */
tid = INLINE_SYSCALL_CALL (gettid);
else
/* Force load of pd->tid into local variable or register. Otherwise
if a thread exits between ESRCH test and tgkill, we might return
EINVAL, because pd->tid would be cleared by the kernel. */
tid = atomic_forced_read (pd->tid);
int val = INTERNAL_SYSCALL_CALL (tgkill, pid, tid, signo);
return (INTERNAL_SYSCALL_ERROR_P (val)
? INTERNAL_SYSCALL_ERRNO (val) : 0);
int val;
if (__glibc_likely (tid > 0))
{
pid_t pid = __getpid ();
val = INTERNAL_SYSCALL_CALL (tgkill, pid, tid, signo);
val = (INTERNAL_SYSCALL_ERROR_P (val)
? INTERNAL_SYSCALL_ERRNO (val) : 0);
}
else
val = ESRCH;
return val;
}
/* Some architectures (for instance arm) might pull raise through libgcc, so
avoid the symbol version if it ends up being used on ld.so. */
#if !IS_IN(rtld)
libc_hidden_def (__pthread_kill)
versioned_symbol (libc, __pthread_kill, pthread_kill, GLIBC_2_34);
#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34)
# if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libc, __pthread_kill, pthread_kill, GLIBC_2_0);
# endif
#endif