On 11/04/2018 12:22, Stefan Liebler wrote:
Hi,
the recent commit b4a5d26d8835d972995f0a0a2f805a8845bafa0b
"linux: Consolidate sigaction implementation" changed the definition
of struct sigaction for s390 (31bit). Unfortunately the order of the
fields were wrong.
This leads to blocking testcases e.g. nptl/tst-sem11. A thread which blocks due to sem_wait() is cancelled via pthread_cancel() and the signal-handler sigcancel_handler (see <glibc-src>/nptl/nptl-init.c is called. But it just returns as the siginfo_t argument is not setup by the kernel. Then the main-thread is blocking due to pthread_join().
The flag SA_SIGINFO is set in sa_flags in struct sigaction and is copied to the "kernel_sigaction.h" struct by the sigaction() call, but due to the wrong ordering of the struct fields, the kernel does not recognize it.
This patch is fixing the definition of s390-kernel_sigaction.h struct for 31bit.
Okay to commit?
Thanks for checking on it (I wish the LinuxONE access account wouldn't have
a 3 month expiration limit). LGTM, only the comment sounds a bit confusing.
Bye
Stefan
ChangeLog:
* sysdeps/unix/sysv/linux/s390/kernel_sigaction.h
(struct kernel_sigaction): Use the same definition
on 31bit as is used on 64bit.
20180411_s390_kernel_sigaction.patch
commit 404f5a0eac37d4c85e027c7b7fc64cb3ecbfc894
Author: Stefan Liebler <stli@linux.vnet.ibm.com>
Date: Wed Apr 11 16:57:48 2018 +0200
S390: Fix struct sigaction for 31bit in kernel_sigaction.h.
The recent commit b4a5d26d8835d972995f0a0a2f805a8845bafa0b
"linux: Consolidate sigaction implementation" changed the definition
of struct sigaction for s390 (31bit). Unfortunately the order of the
fields were wrong.
This leads to blocking testcases e.g. nptl/tst-sem11.
A thread which blocks due to sem_wait() is cancelled via pthread_cancel()
and the signal-handler sigcancel_handler (see <glibc-src>/nptl/nptl-init.c
is called.
But it just returns as the siginfo_t argument is not setup by the kernel.
Then the main-thread is blocking due to pthread_join().
The flag SA_SIGINFO is set in sa_flags in struct sigaction and
is copied to the "kernel_sigaction.h" struct by the sigaction() call,
but due to the wrong ordering of the struct fields,
the kernel does not recognize it.
diff --git a/sysdeps/unix/sysv/linux/s390/kernel_sigaction.h b/sysdeps/unix/sysv/linux/s390/kernel_sigaction.h
index a8beaf7347..28a1aa0f37 100644
--- a/sysdeps/unix/sysv/linux/s390/kernel_sigaction.h
+++ b/sysdeps/unix/sysv/linux/s390/kernel_sigaction.h
@@ -11,15 +11,30 @@ struct kernel_sigaction
void (*_sa_sigaction)(int, siginfo_t *, void *);
} _u;
#define k_sa_handler _u._sa_handler
-#ifndef __s390x__
- sigset_t sa_mask;
- unsigned long sa_flags;
- void (*sa_restorer)(void);
-#else
+ /* The rt_sigaction-syscall (which is currently used in glibc)
+ expects this struct on 31bit (real 31bit-kernel or compat-mode) and 64bit!
+ See <kernel-src>/include/linux/signal_types.h: struct sigaction
+ or <kernel-src>/include/linux/compat.h: struct compat_sigaction.
+
+ The sigaction-syscall (which is currently not used in glibc and was never
+ used on s390x 64bit) expects the kernel struct old_sigaction
+ and struct compat_old_sigaction. There the order of the fields is:
+ -_sa_handler / _sa_sigaction
+ -sa_mask
+ -sa_flags
+ -sa_restorer
+ See the same kernel-headers as mentioned above.
+
+ The definition of struct sigaction in
+ <kernel-src>/arch/s390/include/uapi/asm/signal.h
+ (only used for kernel-uapi)
+ is currently using the struct-definition for rt_sigaction-syscall on 64bit
+ and the struct-definition for sigaction-syscall on 31bit.
+ Thus we can't simply copy this definition here.
+ Note: This kernel-uapi-defintion will also be fixed! */
I would use just:
/* The 'struct sigaction' definition in s390 kernel header
arch/s390/include/uapi/asm/signal.h is used for __NR_rt_sigaction
on 64 bits and for __NR_sigaction for 31 bits.
The expected layout for __NR_rt_sigaction for 31 bits is either
'struct sigaction' from include/linux/signal_types.h or
'struct compat_sigaction' from include/linux/compat.h.
So for __NR_rt_sigaction we can use the same layout for both s390x
and s390. */
unsigned long sa_flags;
void (*sa_restorer)(void);
sigset_t sa_mask;
-#endif
};
#define SET_SA_RESTORER(kact, act) \