Re: [PATCH] Use inline syscalls for non-cancellable versions

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

HI tile issue now fixed, I will commit it soon unless someone opposes it.

On 20-05-2015 11:19, Adhemerval Zanella wrote:
> Hi
> 
> This patch is one of the required adjustments for the fix for bz12683
> (Race conditions in pthread cancellation) and the idea is to not rely
> on the non-cancelable entry points for cancelable syscalls (since the
> upcoming fill will remove them).
>  
> This patch uses inline calls (through INLINE_SYSCALL macro) to define
> the non-cancellable functions macros to avoid use of the
> syscall_nocancel entrypoint.
> 
> Tested on i386, x86_64, x32, powerpc32, powerpc64, arm, and aarch64.
> 
> ---
> 
> 	* sysdeps/unix/sysv/linux/not-cancel.h (open_not_cancel): Rewrite to
> 	be an inline implementation regardless of library is built within.
> 	(open_not_cancel_2): Likewise.
> 	(__read_nocancel): Likewise.
> 	(__write_nocancel): Likewise.
> 	(openat_not_cancel): Likewise.
> 	(openat_not_cancel_3): Likewise.
> 	(openat64_not_cancel): Likewise.
> 	(openat64_not_cancel_3): Likewise.
> 	(__close_nocancel): Likewise.
> 	(pause_not_cancel): Likewise.
> 	(nanosleep_not_cancel): Likewise.
> 	(sigsuspend_not_cancel): Likewise.
> 
> --
> 
> diff --git a/sysdeps/unix/sysv/linux/not-cancel.h b/sysdeps/unix/sysv/linux/not-cancel.h
> index 62d487f..8a358fd 100644
> --- a/sysdeps/unix/sysv/linux/not-cancel.h
> +++ b/sysdeps/unix/sysv/linux/not-cancel.h
> @@ -17,48 +17,48 @@
>     License along with the GNU C Library; if not, see
>     <http://www.gnu.org/licenses/>.  */
>  
> +#ifndef NOT_CANCEL_H
> +# define NOT_CANCEL_H
> +
>  #include <sysdep.h>
> +#include <errno.h>
> +#include <unistd.h>
> +#include <sys/syscall.h>
>  
> -#if IS_IN (libc) || IS_IN (libpthread) || IS_IN (librt)
> -extern int __open_nocancel (const char *, int, ...) attribute_hidden;
> -extern int __close_nocancel (int) attribute_hidden;
> -extern int __read_nocancel (int, void *, size_t) attribute_hidden;
> -extern int __write_nocancel (int, const void *, size_t) attribute_hidden;
> -extern pid_t __waitpid_nocancel (pid_t, int *, int) attribute_hidden;
> -extern int __openat_nocancel (int fd, const char *fname, int oflag,
> -				mode_t mode) attribute_hidden;
> -extern int __openat64_nocancel (int fd, const char *fname, int oflag,
> -				  mode_t mode) attribute_hidden;
> +/* Uncancelable open.  */
> +#ifdef __NR_open
> +# define open_not_cancel(name, flags, mode) \
> +   INLINE_SYSCALL (open, 3, name, flags, mode)
> +# define open_not_cancel_2(name, flags) \
> +   INLINE_SYSCALL (open, 2, name, flags)
>  #else
> -# define __open_nocancel(name, ...) __open (name, __VA_ARGS__)
> -# define __close_nocancel(fd) __close (fd)
> -# define __read_nocancel(fd, buf, len) __read (fd, buf, len)
> -# define __write_nocancel(fd, buf, len) __write (fd, buf, len)
> -# define __waitpid_nocancel(pid, stat_loc, options) \
> -  __waitpid (pid, stat_loc, options)
> -# define __openat_nocancel(fd, fname, oflag, mode) \
> -  openat (fd, fname, oflag, mode)
> -# define __openat64_nocancel(fd, fname, oflag, mode) \
> -  openat64 (fd, fname, oflag, mode)
> +# define open_not_cancel(name, flags, mode) \
> +   INLINE_SYSCALL (openat, 4, AT_FDCWD, name, flags, mode)
> +# define open_not_cancel_2(name, flags) \
> +   INLINE_SYSCALL (openat, 3, AT_FDCWD, name, flags)
>  #endif
>  
> -/* Uncancelable open.  */
> -#define open_not_cancel(name, flags, mode) \
> -   __open_nocancel (name, flags, mode)
> -#define open_not_cancel_2(name, flags) \
> -   __open_nocancel (name, flags)
> +/* Uncancelable read.  */
> +#define __read_nocancel(fd, buf, len) \
> +  INLINE_SYSCALL (read, 3, fd, buf, len)
> +
> +/* Uncancelable write.  */
> +#define __write_nocancel(fd, buf, len) \
> +  INLINE_SYSCALL (write, 3, fd, buf, len)
>  
>  /* Uncancelable openat.  */
>  #define openat_not_cancel(fd, fname, oflag, mode) \
> -  __openat_nocancel (fd, fname, oflag, mode)
> +  INLINE_SYSCALL (openat, 4, fd, fname, oflag, mode)
>  #define openat_not_cancel_3(fd, fname, oflag) \
> -  __openat_nocancel (fd, fname, oflag, 0)
> +  INLINE_SYSCALL (openat, 3, fd, fname, oflag)
>  #define openat64_not_cancel(fd, fname, oflag, mode) \
> -  __openat64_nocancel (fd, fname, oflag, mode)
> +  INLINE_SYSCALL (openat, 4, fd, fname, oflag | O_LARGEFILE, mode)
>  #define openat64_not_cancel_3(fd, fname, oflag) \
> -  __openat64_nocancel (fd, fname, oflag, 0)
> +  INLINE_SYSCALL (openat, 3, fd, fname, oflag | O_LARGEFILE)
>  
>  /* Uncancelable close.  */
> +#define __close_nocancel(fd) \
> +  INLINE_SYSCALL (close, 1, fd)
>  #define close_not_cancel(fd) \
>    __close_nocancel (fd)
>  #define close_not_cancel_no_status(fd) \
> @@ -83,17 +83,27 @@ extern int __openat64_nocancel (int fd, const char *fname, int oflag,
>    __fcntl_nocancel (fd, cmd, val)
>  
>  /* Uncancelable waitpid.  */
> -#define waitpid_not_cancel(pid, stat_loc, options) \
> +#define __waitpid_nocancel(pid, stat_loc, options) \
>    INLINE_SYSCALL (wait4, 4, pid, stat_loc, options, NULL)
> +#define waitpid_not_cancel(pid, stat_loc, options) \
> +  __waitpid_nocancel(pid, stat_loc, options)
>  
>  /* Uncancelable pause.  */
>  #define pause_not_cancel() \
> -  __pause_nocancel ()
> +  ({ sigset_t set; 							     \
> +     int __rc = INLINE_SYSCALL (rt_sigprocmask, 4, SIG_BLOCK, NULL, &set,    \
> +				_NSIG / 8);				     \
> +     if (__rc == 0)							     \
> +       __rc = INLINE_SYSCALL (rt_sigsuspend, 2, &set, _NSIG / 8);	     \
> +     __rc;								     \
> +  })
>  
>  /* Uncancelable nanosleep.  */
>  #define nanosleep_not_cancel(requested_time, remaining) \
> -  __nanosleep_nocancel (requested_time, remaining)
> +  INLINE_SYSCALL (nanosleep, 2, requested_time, remaining)
>  
>  /* Uncancelable sigsuspend.  */
>  #define sigsuspend_not_cancel(set) \
> -  __sigsuspend_nocancel (set)
> +  INLINE_SYSCALL (rt_sigsuspend, 2, set, _NSIG / 8)
> +
> +#endif /* NOT_CANCEL_H  */
> diff --git a/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c b/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c
> index 5b6bb51..3578ea8 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c
> +++ b/sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c
> @@ -41,7 +41,7 @@ __get_clockfreq (void)
>       contains at least one line like:
>       timebase        : 33333333
>       We search for this line and convert the number into an integer.  */
> -  int fd = __open_nocancel ("/proc/cpuinfo", O_RDONLY);
> +  int fd = open_not_cancel_2 ("/proc/cpuinfo", O_RDONLY);
>    if (__glibc_likely (fd != -1))
>      return result;
>