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SubjectRe: 2.6.35-rc3 deadlocks on semaphore operations
On 06/18/2010 04:49 PM, Christoph Lameter wrote:
> linux-2.6$ strace -p21561
> Process 21561 attached - interrupt to quit
> semop(32768, {{0, -1, SEM_UNDO}}, 1
>
> linux-2.6$ strace -p21751
> Process 21751 attached - interrupt to quit
> semop(32768, {{0, -1, SEM_UNDO}}, 1
>
> linux-2.6$ strace -p21792
> Process 21792 attached - interrupt to quit
> semop(32768, {{0, -1, SEM_UNDO}}, 1
>
> linux-2.6$ strace -p21793
> Process 21793 attached - interrupt to quit
> semop(32768, {{0, -1, SEM_UNDO}}, 1
>
>
What are the semaphore values?

Could you run
$ ipcs
$ cat /proc/sysvipc/sem
$ ./getall 32768 -v

getall is attached.

--
Manfred

/*
* Copyright (C) 1999 by Manfred Spraul.
*
* Redistribution of this file is permitted under the terms of the GNU
* General Public License (GPL)
* $Header: /home/manfred/cvs-tree/manfred/ipcsem/getall.c,v 1.2 2001/02/27 15:44:32 manfred Exp $
*/
#include <sys/sem.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <assert.h>

#define TRUE 1
#define FALSE 0

union semun {
int val;
struct semid_ds *buf;
unsigned short int *array;
struct seminfo* __buf;
};

int main(int argc,char** argv)
{
int id;
int key;
int res;
int nsems;
printf("getall <id> [-v]\n");
if(argc < 2 || argc > 3) {
printf("Invalid parameters.\n");
return 1;
}
if (argc == 3 && strcmp(argv[2], "-v")) {
printf("Invalid parameters.\n");
return 1;
}
key = atoi(argv[1]);
if(key < 0) {
printf("Invalid parameters.\n");
return 1;
}
/* id = semget(key,1,0);
if(id == -1) {
printf(" findkey() failed.\n");
return 1;
} */
id = key;
{
union semun arg;
struct semid_ds info;
arg.buf = &info;
res = semctl(id,0,2,arg);

if(res==-1) {
printf("semctl(2) failed (%d).\n",errno);
return 1;
}
nsems = info.sem_nsems;
printf("found %d semaphores.\n",nsems);
}
{
union semun arg;
unsigned short *pv;
int i;
pv = malloc(sizeof(unsigned short)*nsems);
arg.array = pv;
res = semctl(id,nsems, GETALL, arg);
if(res==-1) {
printf("GETALL failed.\n");
return 1;
}
for(i=0;i<nsems;i++) {
if (argc == 3) {
printf(" %3d: %3d (cnt %3d zcnt %3d)\n",
i, pv[i], semctl(id, i, GETNCNT),
semctl(id, i, GETZCNT));
} else {
if(i%16 == 0)
printf("\n 0x%4.4x:",i);
printf(" %3d",pv[i]);
}
}
printf("\n");
}
return 0;
}
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