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lockd: nlmclnt_reclaim(): avoid stack overflow 

Even though nlmclnt_reclaim() is only one call into the stack frame,
928 bytes on the stack seems like a lot. Recode to dynamically
allocate the request structure once from within the reclaimer task,
then pass this pointer into nlmclnt_reclaim() for reuse on
subsequent calls.

smatch analysis:

fs/lockd/clntproc.c:620 nlmclnt_reclaim() warn: 'reqst' puts
 928 bytes on stack

Also remove redundant assignment of 0 after memset.

Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Tim Gardner 2013-02-13 08:40:16 -07:00 committed by J. Bruce Fields
parent deb4534f4f
commit f25cc71e63
3 changed files with 15 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
fs/lockd/clntlock.c
View File

@ -220,10 +220,19 @@ reclaimer(void *ptr)
{ {
struct nlm_host *host = (struct nlm_host *) ptr; struct nlm_host *host = (struct nlm_host *) ptr;
struct nlm_wait *block; struct nlm_wait *block;
struct nlm_rqst *req;
struct file_lock *fl, *next; struct file_lock *fl, *next;
u32 nsmstate; u32 nsmstate;
struct net *net = host->net; struct net *net = host->net;
req = kmalloc(sizeof(*req), GFP_KERNEL);
if (!req) {
printk(KERN_ERR "lockd: reclaimer unable to alloc memory."
" Locks for %s won't be reclaimed!\n",
host->h_name);
return 0;
}
allow_signal(SIGKILL); allow_signal(SIGKILL);
down_write(&host->h_rwsem); down_write(&host->h_rwsem);
@ -253,7 +262,7 @@ reclaimer(void *ptr)
*/ */
if (signalled()) if (signalled())
continue; continue;
if (nlmclnt_reclaim(host, fl) != 0) if (nlmclnt_reclaim(host, fl, req) != 0)
continue; continue;
list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
if (host->h_nsmstate != nsmstate) { if (host->h_nsmstate != nsmstate) {
@ -279,5 +288,6 @@ reclaimer(void *ptr)
/* Release host handle after use */ /* Release host handle after use */
nlmclnt_release_host(host); nlmclnt_release_host(host);
lockd_down(net); lockd_down(net);
kfree(req);
return 0; return 0;
} }

6
fs/lockd/clntproc.c
View File

@ -615,17 +615,15 @@ nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
* RECLAIM: Try to reclaim a lock * RECLAIM: Try to reclaim a lock
*/ */
int int
nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl) nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
struct nlm_rqst *req)
{ {
struct nlm_rqst reqst, *req;
int status; int status;
req = &reqst;
memset(req, 0, sizeof(*req)); memset(req, 0, sizeof(*req));
locks_init_lock(&req->a_args.lock.fl); locks_init_lock(&req->a_args.lock.fl);
locks_init_lock(&req->a_res.lock.fl); locks_init_lock(&req->a_res.lock.fl);
req->a_host = host; req->a_host = host;
req->a_flags = 0;
/* Set up the argument struct */ /* Set up the argument struct */
nlmclnt_setlockargs(req, fl); nlmclnt_setlockargs(req, fl);

3
include/linux/lockd/lockd.h
View File

@ -212,7 +212,8 @@ int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
__be32 nlmclnt_grant(const struct sockaddr *addr, __be32 nlmclnt_grant(const struct sockaddr *addr,
const struct nlm_lock *lock); const struct nlm_lock *lock);
void nlmclnt_recovery(struct nlm_host *); void nlmclnt_recovery(struct nlm_host *);
int nlmclnt_reclaim(struct nlm_host *, struct file_lock *); int nlmclnt_reclaim(struct nlm_host *, struct file_lock *,
struct nlm_rqst *);
void nlmclnt_next_cookie(struct nlm_cookie *); void nlmclnt_next_cookie(struct nlm_cookie *);
/* /*