fcntl couldn't lock /dev/null and hangHow to track down the copy and move operations of files and folders?Get...
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fcntl couldn't lock /dev/null and hang
How to track down the copy and move operations of files and folders?Get exclusive lock constant? In ctypes it is O_EXLOCKDoes the /dev/null file actually have a fixed size?How to lock files with custom-set password?Lock file and release itHow do I use /dev/sdb1 to reduce the strain on /dev/sda1Lock screen halts file copying in NautilusDifference in file count (Linux and Windows)Moved a folder to /dev. Folder has disappeared after rebooting/dev/null questions
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}
A minimal working example, but only for my machine:
int main(int argc, char* argv[]) {
int fd = open ("/dev/null", O_RDWR|O_CREAT);
if (fd < 0) {
printf("Failed to open filen");
}
struct flock lock;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
int res = fcntl(fd, F_SETLKW,&lock); // this hangs
if (res < 0) {
printf("Failed to lockn");
}
close (fd);
return (0);
}
The program above hangs only on my machine, and completed instantly on 7 other machines. Is there anything that I can look into to investigate this problem?
strace shows that fcntl was getting stuck when the program (./t) was killed by ^C.
5249 execve("./t", ["./t"], [/* 23 vars */]) = 0
5249 brk(NULL) = 0x1cf6000
5249 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5249 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
5249 open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
5249 fstat(3, {st_mode=S_IFREG|0644, st_size=98358, ...}) = 0
5249 mmap(NULL, 98358, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f31a1118000
5249 close(3) = 0
5249 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5249 open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
5249 read(3, "177ELF21133>1Pt2"..., 832) = 832
5249 fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1117000
5249 mmap(NULL, 3971488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f31a0b42000
5249 mprotect(0x7f31a0d02000, 2097152, PROT_NONE) = 0
5249 mmap(0x7f31a0f02000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f31a0f02000
5249 mmap(0x7f31a0f08000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f31a0f08000
5249 close(3) = 0
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1116000
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1115000
5249 arch_prctl(ARCH_SET_FS, 0x7f31a1116700) = 0
5249 mprotect(0x7f31a0f02000, 16384, PROT_READ) = 0
5249 mprotect(0x600000, 4096, PROT_READ) = 0
5249 mprotect(0x7f31a1131000, 4096, PROT_READ) = 0
5249 munmap(0x7f31a1118000, 98358) = 0
5249 open("/dev/null", O_RDWR|O_CREAT, 03777762203636510) = 3
5249 fcntl(3, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
5249 --- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} ---
5249 +++ killed by SIGINT +++
files
asked 50 mins ago
qspqsp
88110
add a comment |
A minimal working example, but only for my machine:
int main(int argc, char* argv[]) {
int fd = open ("/dev/null", O_RDWR|O_CREAT);
if (fd < 0) {
printf("Failed to open filen");
}
struct flock lock;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
int res = fcntl(fd, F_SETLKW,&lock); // this hangs
if (res < 0) {
printf("Failed to lockn");
}
close (fd);
return (0);
}
The program above hangs only on my machine, and completed instantly on 7 other machines. Is there anything that I can look into to investigate this problem?
strace shows that fcntl was getting stuck when the program (./t) was killed by ^C.
5249 execve("./t", ["./t"], [/* 23 vars */]) = 0
5249 brk(NULL) = 0x1cf6000
5249 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5249 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
5249 open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
5249 fstat(3, {st_mode=S_IFREG|0644, st_size=98358, ...}) = 0
5249 mmap(NULL, 98358, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f31a1118000
5249 close(3) = 0
5249 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5249 open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
5249 read(3, "177ELF21133>1Pt2"..., 832) = 832
5249 fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1117000
5249 mmap(NULL, 3971488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f31a0b42000
5249 mprotect(0x7f31a0d02000, 2097152, PROT_NONE) = 0
5249 mmap(0x7f31a0f02000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f31a0f02000
5249 mmap(0x7f31a0f08000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f31a0f08000
5249 close(3) = 0
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1116000
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1115000
5249 arch_prctl(ARCH_SET_FS, 0x7f31a1116700) = 0
5249 mprotect(0x7f31a0f02000, 16384, PROT_READ) = 0
5249 mprotect(0x600000, 4096, PROT_READ) = 0
5249 mprotect(0x7f31a1131000, 4096, PROT_READ) = 0
5249 munmap(0x7f31a1118000, 98358) = 0
5249 open("/dev/null", O_RDWR|O_CREAT, 03777762203636510) = 3
5249 fcntl(3, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
5249 --- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} ---
5249 +++ killed by SIGINT +++
files
asked 50 mins ago
qspqsp
88110
First thing to look into would bestrace.
– Jos
43 mins ago
@Jos Thanks, I added strace output, what else I can look into?
– qsp
31 mins ago
Why do you want a lock on/dev/null?
– vidarlo
2 mins ago
add a comment |
A minimal working example, but only for my machine:
int main(int argc, char* argv[]) {
int fd = open ("/dev/null", O_RDWR|O_CREAT);
if (fd < 0) {
printf("Failed to open filen");
}
struct flock lock;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
int res = fcntl(fd, F_SETLKW,&lock); // this hangs
if (res < 0) {
printf("Failed to lockn");
}
close (fd);
return (0);
}
The program above hangs only on my machine, and completed instantly on 7 other machines. Is there anything that I can look into to investigate this problem?
strace shows that fcntl was getting stuck when the program (./t) was killed by ^C.
5249 execve("./t", ["./t"], [/* 23 vars */]) = 0
5249 brk(NULL) = 0x1cf6000
5249 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5249 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
5249 open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
5249 fstat(3, {st_mode=S_IFREG|0644, st_size=98358, ...}) = 0
5249 mmap(NULL, 98358, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f31a1118000
5249 close(3) = 0
5249 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5249 open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
5249 read(3, "177ELF21133>1Pt2"..., 832) = 832
5249 fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1117000
5249 mmap(NULL, 3971488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f31a0b42000
5249 mprotect(0x7f31a0d02000, 2097152, PROT_NONE) = 0
5249 mmap(0x7f31a0f02000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f31a0f02000
5249 mmap(0x7f31a0f08000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f31a0f08000
5249 close(3) = 0
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1116000
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1115000
5249 arch_prctl(ARCH_SET_FS, 0x7f31a1116700) = 0
5249 mprotect(0x7f31a0f02000, 16384, PROT_READ) = 0
5249 mprotect(0x600000, 4096, PROT_READ) = 0
5249 mprotect(0x7f31a1131000, 4096, PROT_READ) = 0
5249 munmap(0x7f31a1118000, 98358) = 0
5249 open("/dev/null", O_RDWR|O_CREAT, 03777762203636510) = 3
5249 fcntl(3, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
5249 --- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} ---
5249 +++ killed by SIGINT +++
files
asked 50 mins ago
qspqsp
88110
A minimal working example, but only for my machine:
int main(int argc, char* argv[]) {
int fd = open ("/dev/null", O_RDWR|O_CREAT);
if (fd < 0) {
printf("Failed to open filen");
}
struct flock lock;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
int res = fcntl(fd, F_SETLKW,&lock); // this hangs
if (res < 0) {
printf("Failed to lockn");
}
close (fd);
return (0);
}
The program above hangs only on my machine, and completed instantly on 7 other machines. Is there anything that I can look into to investigate this problem?
strace shows that fcntl was getting stuck when the program (./t) was killed by ^C.
5249 execve("./t", ["./t"], [/* 23 vars */]) = 0
5249 brk(NULL) = 0x1cf6000
5249 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5249 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
5249 open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
5249 fstat(3, {st_mode=S_IFREG|0644, st_size=98358, ...}) = 0
5249 mmap(NULL, 98358, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f31a1118000
5249 close(3) = 0
5249 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5249 open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
5249 read(3, "177ELF21133>1Pt2"..., 832) = 832
5249 fstat(3, {st_mode=S_IFREG|0755, st_size=1868984, ...}) = 0
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1117000
5249 mmap(NULL, 3971488, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f31a0b42000
5249 mprotect(0x7f31a0d02000, 2097152, PROT_NONE) = 0
5249 mmap(0x7f31a0f02000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c0000) = 0x7f31a0f02000
5249 mmap(0x7f31a0f08000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f31a0f08000
5249 close(3) = 0
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1116000
5249 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f31a1115000
5249 arch_prctl(ARCH_SET_FS, 0x7f31a1116700) = 0
5249 mprotect(0x7f31a0f02000, 16384, PROT_READ) = 0
5249 mprotect(0x600000, 4096, PROT_READ) = 0
5249 mprotect(0x7f31a1131000, 4096, PROT_READ) = 0
5249 munmap(0x7f31a1118000, 98358) = 0
5249 open("/dev/null", O_RDWR|O_CREAT, 03777762203636510) = 3
5249 fcntl(3, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
5249 --- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} ---
5249 +++ killed by SIGINT +++
files
files
asked 50 mins ago
qspqsp
88110
asked 50 mins ago
qspqsp
88110
edited 31 mins ago
qsp
asked 50 mins ago
qspqsp
88110
asked 50 mins ago
qspqsp
88110
asked 50 mins ago
qspqsp
88110
88110
First thing to look into would bestrace.
– Jos
43 mins ago
@Jos Thanks, I added strace output, what else I can look into?
– qsp
31 mins ago
Why do you want a lock on/dev/null?
– vidarlo
2 mins ago
add a comment |
First thing to look into would bestrace.
– Jos
43 mins ago
@Jos Thanks, I added strace output, what else I can look into?
– qsp
31 mins ago
Why do you want a lock on/dev/null?
– vidarlo
2 mins ago
First thing to look into would be
strace.– Jos
43 mins ago
First thing to look into would be
strace.– Jos
43 mins ago
@Jos Thanks, I added strace output, what else I can look into?
– qsp
31 mins ago
@Jos Thanks, I added strace output, what else I can look into?
– qsp
31 mins ago
Why do you want a lock on
/dev/null?– vidarlo
2 mins ago
Why do you want a lock on
/dev/null?– vidarlo
2 mins ago
add a comment |
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First thing to look into would be
strace.– Jos
43 mins ago
@Jos Thanks, I added strace output, what else I can look into?
– qsp
31 mins ago
Why do you want a lock on
/dev/null?– vidarlo
2 mins ago