[stgt] [PATCH] handle SEM Key clash between multiple tgt instances

[FUJITA Tomonori]

On Mon, 14 Mar 2011 15:26:45 +0200
Or Gerlitz <ogerlitz at mellanox.com> wrote:

> From: Roland Friedwagner <roland.friedwagner at wu.ac.at>
> 
> commit e2f95b537 "semaphore key clash with Open-iSCSI initiator" didn't
> address a further clash introduced when multiple tgt instances are
> running. Address that by creating the IPC semaphore keyid based on
> the managment socket file using ftok(3).
> 
> Signed-off-by: Roland Friedwagner <roland.friedwagner at wu.ac.at>
> Signed-off-by: Or Gerlitz <ogerlitz at mellanox.com>
> 
> ---
>  usr/log.c    |   15 +++++++++++++--
>  usr/mgmt.c   |    9 +++++----
>  usr/tgtadm.c |    6 +++---
>  3 files changed, 21 insertions(+), 9 deletions(-)
> 
> diff --git a/usr/log.c b/usr/log.c
> index 06cd8bf..2f0c4d4 100644
> --- a/usr/log.c
> +++ b/usr/log.c
> @@ -33,7 +33,6 @@
> 
>  #include "log.h"
> 
> -#define SEMKEY	0x54475444L /* TGTD */
>  #define LOGDBG 0
> 
>  #if LOGDBG
> @@ -50,6 +49,8 @@ static pid_t pid;
>  static int logarea_init (int size)
>  {
>  	int shmid;
> +	extern char mgmt_path[];
> +	key_t semkey;
> 
>  	logdbg(stderr,"enter logarea_init\n");
> 
> @@ -109,13 +110,23 @@ static int logarea_init (int size)
> 
>  	shmctl(shmid, IPC_RMID, NULL);
> 
> -	if ((la->semid = semget(SEMKEY, 1, 0666 | IPC_CREAT)) < 0) {
> +	if ((semkey = ftok(mgmt_path, 'a')) < 0) {
> +		syslog(LOG_ERR, "semkey failed %d", errno);
> +		return 1;
> +	}
> +
> +        if ((semget(semkey, 0, IPC_EXCL)) > 0) {
> +		/* Semkey may exists after SIGKILL tgtd */
> +		syslog(LOG_WARNING, "semkey 0x%x already exists", semkey);
> +	}
> +	if ((la->semid = semget(semkey, 1, 0666 | IPC_CREAT)) < 0) {
>  		syslog(LOG_ERR, "semget failed %d", errno);
>  		shmdt(la->buff);
>  		shmdt(la->start);
>  		shmdt(la);
>  		return 1;
>  	}
> +	syslog(LOG_INFO, "semkey 0x%x", semkey);
> 
>  	la->semarg.val=1;
>  	if (semctl(la->semid, 0, SETVAL, la->semarg) < 0) {
> diff --git a/usr/mgmt.c b/usr/mgmt.c
> index 5a6a03b..fb703a6 100644
> --- a/usr/mgmt.c
> +++ b/usr/mgmt.c
> @@ -59,6 +59,7 @@ struct mgmt_task {
>  };
> 
>  static int ipc_fd;
> +char mgmt_path[256];
> 
>  static void set_show_results(struct tgtadm_rsp *rsp, int *err)
>  {
> @@ -567,7 +568,7 @@ int ipc_init(void)
>  	extern short control_port;
>  	int fd, err;
>  	struct sockaddr_un addr;
> -	char path[256];
> +	extern char mgmt_path[];

No need?


>  	fd = socket(AF_LOCAL, SOCK_STREAM, 0);
>  	if (fd < 0) {
> @@ -575,11 +576,11 @@ int ipc_init(void)
>  		return -1;
>  	}
> 
> -	sprintf(path, "%s.%d", TGT_IPC_NAMESPACE, control_port);
> -	unlink(path);
> +	sprintf(mgmt_path, "%s.%d", TGT_IPC_NAMESPACE, control_port);
> +	unlink(mgmt_path);
>  	memset(&addr, 0, sizeof(addr));
>  	addr.sun_family = AF_LOCAL;
> -	strncpy(addr.sun_path, path, sizeof(addr.sun_path));
> +	strncpy(addr.sun_path, mgmt_path, sizeof(addr.sun_path));
> 
>  	err = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
>  	if (err) {
> diff --git a/usr/tgtadm.c b/usr/tgtadm.c
> index e81a419..9821917 100644
> --- a/usr/tgtadm.c
> +++ b/usr/tgtadm.c
> @@ -190,7 +190,7 @@ static int ipc_mgmt_connect(int *fd)
>  {
>  	int err;
>  	struct sockaddr_un addr;
> -	char path[256];
> +	char mgmt_path[256];
> 
>  	*fd = socket(AF_LOCAL, SOCK_STREAM, 0);
>  	if (*fd < 0) {
> @@ -200,8 +200,8 @@ static int ipc_mgmt_connect(int *fd)
> 
>  	memset(&addr, 0, sizeof(addr));
>  	addr.sun_family = AF_LOCAL;
> -	sprintf(path, "%s.%d", TGT_IPC_NAMESPACE, control_port);
> -	strncpy(addr.sun_path, path, sizeof(addr.sun_path));
> +	sprintf(mgmt_path, "%s.%d", TGT_IPC_NAMESPACE, control_port);
> +	strncpy(addr.sun_path, mgmt_path, sizeof(addr.sun_path));

Why do we need to rename path to mgmt_path in tgtadm.c?
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