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misc: Set generic pselect as ENOSYS

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The generic pselect implementation has the very specific race condition
that motived the creation of the pselect syscall (no atomicity in
signal mask set/reset).  Using it as generic implementation is
counterproductive  Also currently only microblaze uses it as fallback
when used on kernel prior 3.15.

This patch moves the generic implementation to a microblaze specific
one, sets the generic internal as a ENOSYS, and cleanups the Linux
generic implementation.

The microblaze implementation mimics the previous Linux generic one,
where it either uses pselect6 directly if __ASSUME_PSELECT or a
first try pselect6 then the fallback otherwise.

Checked on x86_64-linux-gnu and microblaze-linux-gnu.
This commit is contained in:
Adhemerval Zanella
2019-11-14 18:18:24 -03:00
parent 102b5b0caf
commit 8781c1301d
3 changed files with 80 additions and 76 deletions
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46
misc/pselect.c
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@ -17,12 +17,7 @@
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <signal.h>
#include <stddef.h> /* For NULL. */
#include <sys/time.h>
#include <sys/select.h>
#include <sysdep-cancel.h>
/* Check the first NFDS descriptors each in READFDS (if not NULL) for read
readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
@ -34,43 +29,8 @@ int
__pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
const struct timespec *timeout, const sigset_t *sigmask)
{
struct timeval tval;
int retval;
sigset_t savemask;
/* Change nanosecond number to microseconds. This might mean losing
precision and therefore the `pselect` should be available. But
for now it is hardly found. */
if (timeout != NULL)
{
/* Catch bugs which would be hidden by the TIMESPEC_TO_TIMEVAL
computations. The division by 1000 truncates values. */
if (__glibc_unlikely (timeout->tv_nsec < 0))
{
__set_errno (EINVAL);
return -1;
}
TIMESPEC_TO_TIMEVAL (&tval, timeout);
}
/* The setting and restoring of the signal mask and the select call
should be an atomic operation. This can't be done without kernel
help. */
if (sigmask != NULL)
__sigprocmask (SIG_SETMASK, sigmask, &savemask);
/* Note the pselect() is a cancellation point. But since we call
select() which itself is a cancellation point we do not have
to do anything here. */
retval = __select (nfds, readfds, writefds, exceptfds,
timeout != NULL ? &tval : NULL);
if (sigmask != NULL)
__sigprocmask (SIG_SETMASK, &savemask, NULL);
return retval;
__set_errno (ENOSYS);
return -1;
}
#ifndef __pselect
weak_alias (__pselect, pselect)
#endif
stub_warning (pselect)