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

[Roland Friedwagner]

Hello,

Am Donnerstag 17 März 2011 schrieb 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?

Yes you are right. It's not absolute needed.

  I thought calculating the sock path again with sprintf()
  in log.c is not necessary, if it is a global and will be 
  calculated only when tgtd main() does call ipc_init().
  I think it whould be a more straight solution.

>
> >  	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?

Only for consistency.

  So when someone, like I did, searches the source for where the socket
  path is referenced, does recognize it's the same thing.

Kind Regards,
Roland

-- 
Roland.Friedwagner at wu.ac.at            Phone: +43 1 31336 5377
IT Services - WU (Vienna University of Economics and Business) 
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