svn commit: r295385 - in head: sys/kern tools/regression/sysvsem

[Kubilay Kocak]

On 8/02/2016 9:12 AM, Jilles Tjoelker wrote:
> Author: jilles
> Date: Sun Feb  7 22:12:39 2016
> New Revision: 295385
> URL: https://svnweb.freebsd.org/changeset/base/295385
> 
> Log:
>   semget(): Check for [EEXIST] error first.
>   
>   Although POSIX literally permits failing with [EINVAL] if IPC_CREAT and
>   IPC_EXCL were both passed, the semaphore set already exists and has fewer
>   semaphores than nsems, this does not allow an application to retry safely:
>   if the [EINVAL] is actually because of the semmsl limit, an infinite loop
>   would result.
>   
>   PR:		206927
> 
> Modified:
>   head/sys/kern/sysv_sem.c
>   head/tools/regression/sysvsem/semtest.c


+infinity for bugfix & issue reference & regression test.

Thank you Jilles!

> Modified: head/sys/kern/sysv_sem.c
> ==============================================================================
> --- head/sys/kern/sysv_sem.c	Sun Feb  7 21:25:08 2016	(r295384)
> +++ head/sys/kern/sysv_sem.c	Sun Feb  7 22:12:39 2016	(r295385)
> @@ -867,6 +867,11 @@ sys_semget(struct thread *td, struct sem
>  		}
>  		if (semid < seminfo.semmni) {
>  			DPRINTF(("found public key\n"));
> +			if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
> +				DPRINTF(("not exclusive\n"));
> +				error = EEXIST;
> +				goto done2;
> +			}
>  			if ((error = ipcperm(td, &sema[semid].u.sem_perm,
>  			    semflg & 0700))) {
>  				goto done2;
> @@ -876,11 +881,6 @@ sys_semget(struct thread *td, struct sem
>  				error = EINVAL;
>  				goto done2;
>  			}
> -			if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
> -				DPRINTF(("not exclusive\n"));
> -				error = EEXIST;
> -				goto done2;
> -			}
>  #ifdef MAC
>  			error = mac_sysvsem_check_semget(cred, &sema[semid]);
>  			if (error != 0)
> 
> Modified: head/tools/regression/sysvsem/semtest.c
> ==============================================================================
> --- head/tools/regression/sysvsem/semtest.c	Sun Feb  7 21:25:08 2016	(r295384)
> +++ head/tools/regression/sysvsem/semtest.c	Sun Feb  7 22:12:39 2016	(r295385)
> @@ -152,6 +152,15 @@ main(int argc, char *argv[])
>  
>  	print_semid_ds(&s_ds, 0600);
>  
> +	errno = 0;
> +	if (semget(semkey, 1, IPC_CREAT | IPC_EXCL | 0600) != -1 ||
> +	    errno != EEXIST)
> +		err(1, "semget IPC_EXCL 1 did not fail with [EEXIST]");
> +	errno = 0;
> +	if (semget(semkey, 2, IPC_CREAT | IPC_EXCL | 0600) != -1 ||
> +	    errno != EEXIST)
> +		err(1, "semget IPC_EXCL 2 did not fail with [EEXIST]");
> +
>  	for (child_count = 0; child_count < 5; child_count++) {
>  		switch ((child_pid = fork())) {
>  		case -1: