On Tue, May 22, 2018 at 10:48:43AM +0800, Xiao Yang wrote: > On 2018/05/22 10:36, Xiong Murphy Zhou wrote: > > On Mon, May 21, 2018 at 01:42:00PM +0800, Xiao Yang wrote: > > > 1) According to fcntl(2) manpage, A single process always gets F_UNLCK in > > > the l_type field when using fcntl(F_GETLK) to acquire the existing lock > > > set by itself because it could convert the existing lock to a new lock > > > unconditionally. So we need another process to check if the lock exists. > > I used to do that, eventaully I deleted it because we don't need > > to check in another process in this case. > Hi Xiong, > > Even if the fix patch[1] has been applied, you always gets F_UNLCK without another process. > > According to fcntl(2) manpage: > F_GETLK > On input to this call, lock describes a lock we would like to place on the file. > If the lock could be placed, fcntl() does not actually place it, but returns F_UNLCK > in the l_type field of lock and leaves the other fields of the structure unchanged. > > A single process can always place a new lock on the file and return F_UNLCK because the existing > lock is set by itself. You are right. My bad. It was included in my initial post. Ack for the patch. Xiong > > [1] https://www.spinics.net/lists/linux-fsdevel/msg123144.html > > Thanks, > Xiao Yang > > > Thanks, > > Xiong > > > > > 2) Remove redundant exit(0). > > > > > > Signed-off-by: Xiao Yang<yangx.jy@xxxxxxxxxxxxxx> > > > --- > > > src/t_locks_execve.c | 24 ++++++++++++++++++------ > > > 1 file changed, 18 insertions(+), 6 deletions(-) > > > > > > diff --git a/src/t_locks_execve.c b/src/t_locks_execve.c > > > index 9ad2dc3..d99d7de 100644 > > > --- a/src/t_locks_execve.c > > > +++ b/src/t_locks_execve.c > > > @@ -8,6 +8,7 @@ > > > #include<errno.h> > > > #include<pthread.h> > > > #include<unistd.h> > > > +#include<sys/types.h> > > > #include<sys/wait.h> > > > > > > static void err_exit(char *op, int errn) > > > @@ -32,12 +33,24 @@ struct flock fl = { > > > > > > static void checklock(int fd) > > > { > > > - if (fcntl(fd, F_GETLK,&fl)< 0) > > > - err_exit("getlk", errno); > > > - if (fl.l_type == F_UNLCK) { > > > - printf("record lock is not preserved across execve(2)\n"); > > > - exit(1); > > > + pid_t pid; > > > + > > > + pid = fork(); > > > + if (pid< 0) > > > + err_exit("fork", errno); > > > + > > > + if (!pid) { > > > + if (fcntl(fd, F_GETLK,&fl)< 0) > > > + err_exit("getlk", errno); > > > + if (fl.l_type == F_UNLCK) { > > > + printf("record lock is not preserved across execve(2)\n"); > > > + exit(1); > > > + } > > > + exit(0); > > > } > > > + > > > + waitpid(pid, NULL, 0); > > > + > > > exit(0); > > > } > > > > > > @@ -52,7 +65,6 @@ int main(int argc, char **argv) > > > if (argc == 3) { > > > fd = atoi(argv[2]); > > > checklock(fd); > > > - exit(0); > > > } > > > > > > fd = open(argv[1], O_WRONLY|O_CREAT, 0755); > > > -- > > > 1.8.3.1 > > > > > > > > > > > > > . > > > > > -- To unsubscribe from this list: send the line "unsubscribe fstests" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
