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authorMatthew Wilcox <willy@infradead.org>2018-07-12 00:02:24 +0300
committerDominique Martinet <dominique.martinet@cea.fr>2018-08-29 07:39:57 +0300
commit996d5b4db4b191f2676cf8775565cab8a5e2753b (patch)
tree586a82cc32aebc85a181bc1cc837062f3d34660f /net/9p/client.c
parent62e3941776fea8678bb8120607039410b1b61a65 (diff)
downloadlinux-996d5b4db4b191f2676cf8775565cab8a5e2753b.tar.xz
9p: Use a slab for allocating requests
Replace the custom batch allocation with a slab. Use an IDR to store pointers to the active requests instead of an array. We don't try to handle P9_NOTAG specially; the IDR will happily shrink all the way back once the TVERSION call has completed. Link: http://lkml.kernel.org/r/20180711210225.19730-6-willy@infradead.org Signed-off-by: Matthew Wilcox <willy@infradead.org> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Ron Minnich <rminnich@sandia.gov> Cc: Latchesar Ionkov <lucho@ionkov.net> Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Diffstat (limited to 'net/9p/client.c')
-rw-r--r--net/9p/client.c238
1 files changed, 85 insertions, 153 deletions
diff --git a/net/9p/client.c b/net/9p/client.c
index deae53a7dffc..88db45966740 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -242,132 +242,102 @@ static struct p9_fcall *p9_fcall_alloc(int alloc_msize)
return fc;
}
+static struct kmem_cache *p9_req_cache;
+
/**
- * p9_tag_alloc - lookup/allocate a request by tag
- * @c: client session to lookup tag within
- * @tag: numeric id for transaction
- *
- * this is a simple array lookup, but will grow the
- * request_slots as necessary to accommodate transaction
- * ids which did not previously have a slot.
- *
- * this code relies on the client spinlock to manage locks, its
- * possible we should switch to something else, but I'd rather
- * stick with something low-overhead for the common case.
+ * p9_req_alloc - Allocate a new request.
+ * @c: Client session.
+ * @type: Transaction type.
+ * @max_size: Maximum packet size for this request.
*
+ * Context: Process context.
+ * Return: Pointer to new request.
*/
-
static struct p9_req_t *
-p9_tag_alloc(struct p9_client *c, u16 tag, unsigned int max_size)
+p9_tag_alloc(struct p9_client *c, int8_t type, unsigned int max_size)
{
- unsigned long flags;
- int row, col;
- struct p9_req_t *req;
+ struct p9_req_t *req = kmem_cache_alloc(p9_req_cache, GFP_NOFS);
int alloc_msize = min(c->msize, max_size);
+ int tag;
- /* This looks up the original request by tag so we know which
- * buffer to read the data into */
- tag++;
-
- if (tag >= c->max_tag) {
- spin_lock_irqsave(&c->lock, flags);
- /* check again since original check was outside of lock */
- while (tag >= c->max_tag) {
- row = (tag / P9_ROW_MAXTAG);
- c->reqs[row] = kcalloc(P9_ROW_MAXTAG,
- sizeof(struct p9_req_t), GFP_ATOMIC);
-
- if (!c->reqs[row]) {
- pr_err("Couldn't grow tag array\n");
- spin_unlock_irqrestore(&c->lock, flags);
- return ERR_PTR(-ENOMEM);
- }
- for (col = 0; col < P9_ROW_MAXTAG; col++) {
- req = &c->reqs[row][col];
- req->status = REQ_STATUS_IDLE;
- init_waitqueue_head(&req->wq);
- }
- c->max_tag += P9_ROW_MAXTAG;
- }
- spin_unlock_irqrestore(&c->lock, flags);
- }
- row = tag / P9_ROW_MAXTAG;
- col = tag % P9_ROW_MAXTAG;
+ if (!req)
+ return NULL;
- req = &c->reqs[row][col];
- if (!req->tc)
- req->tc = p9_fcall_alloc(alloc_msize);
- if (!req->rc)
- req->rc = p9_fcall_alloc(alloc_msize);
+ req->tc = p9_fcall_alloc(alloc_msize);
+ req->rc = p9_fcall_alloc(alloc_msize);
if (!req->tc || !req->rc)
- goto grow_failed;
+ goto free;
p9pdu_reset(req->tc);
p9pdu_reset(req->rc);
-
- req->tc->tag = tag-1;
req->status = REQ_STATUS_ALLOC;
+ init_waitqueue_head(&req->wq);
+ INIT_LIST_HEAD(&req->req_list);
+
+ idr_preload(GFP_NOFS);
+ spin_lock_irq(&c->lock);
+ if (type == P9_TVERSION)
+ tag = idr_alloc(&c->reqs, req, P9_NOTAG, P9_NOTAG + 1,
+ GFP_NOWAIT);
+ else
+ tag = idr_alloc(&c->reqs, req, 0, P9_NOTAG, GFP_NOWAIT);
+ req->tc->tag = tag;
+ spin_unlock_irq(&c->lock);
+ idr_preload_end();
+ if (tag < 0)
+ goto free;
return req;
-grow_failed:
- pr_err("Couldn't grow tag array\n");
+free:
kfree(req->tc);
kfree(req->rc);
- req->tc = req->rc = NULL;
+ kmem_cache_free(p9_req_cache, req);
return ERR_PTR(-ENOMEM);
}
/**
- * p9_tag_lookup - lookup a request by tag
- * @c: client session to lookup tag within
- * @tag: numeric id for transaction
+ * p9_tag_lookup - Look up a request by tag.
+ * @c: Client session.
+ * @tag: Transaction ID.
*
+ * Context: Any context.
+ * Return: A request, or %NULL if there is no request with that tag.
*/
-
struct p9_req_t *p9_tag_lookup(struct p9_client *c, u16 tag)
{
- int row, col;
-
- /* This looks up the original request by tag so we know which
- * buffer to read the data into */
- tag++;
-
- if (tag >= c->max_tag)
- return NULL;
+ struct p9_req_t *req;
- row = tag / P9_ROW_MAXTAG;
- col = tag % P9_ROW_MAXTAG;
+ rcu_read_lock();
+ req = idr_find(&c->reqs, tag);
+ /* There's no refcount on the req; a malicious server could cause
+ * us to dereference a NULL pointer
+ */
+ rcu_read_unlock();
- return &c->reqs[row][col];
+ return req;
}
EXPORT_SYMBOL(p9_tag_lookup);
/**
- * p9_tag_init - setup tags structure and contents
- * @c: v9fs client struct
- *
- * This initializes the tags structure for each client instance.
+ * p9_free_req - Free a request.
+ * @c: Client session.
+ * @r: Request to free.
*
+ * Context: Any context.
*/
-
-static int p9_tag_init(struct p9_client *c)
+static void p9_free_req(struct p9_client *c, struct p9_req_t *r)
{
- int err = 0;
+ unsigned long flags;
+ u16 tag = r->tc->tag;
- c->tagpool = p9_idpool_create();
- if (IS_ERR(c->tagpool)) {
- err = PTR_ERR(c->tagpool);
- goto error;
- }
- err = p9_idpool_get(c->tagpool); /* reserve tag 0 */
- if (err < 0) {
- p9_idpool_destroy(c->tagpool);
- goto error;
- }
- c->max_tag = 0;
-error:
- return err;
+ p9_debug(P9_DEBUG_MUX, "clnt %p req %p tag: %d\n", c, r, tag);
+ spin_lock_irqsave(&c->lock, flags);
+ idr_remove(&c->reqs, tag);
+ spin_unlock_irqrestore(&c->lock, flags);
+ kfree(r->tc);
+ kfree(r->rc);
+ kmem_cache_free(p9_req_cache, r);
}
/**
@@ -379,52 +349,15 @@ error:
*/
static void p9_tag_cleanup(struct p9_client *c)
{
- int row, col;
-
- /* check to insure all requests are idle */
- for (row = 0; row < (c->max_tag/P9_ROW_MAXTAG); row++) {
- for (col = 0; col < P9_ROW_MAXTAG; col++) {
- if (c->reqs[row][col].status != REQ_STATUS_IDLE) {
- p9_debug(P9_DEBUG_MUX,
- "Attempting to cleanup non-free tag %d,%d\n",
- row, col);
- /* TODO: delay execution of cleanup */
- return;
- }
- }
- }
-
- if (c->tagpool) {
- p9_idpool_put(0, c->tagpool); /* free reserved tag 0 */
- p9_idpool_destroy(c->tagpool);
- }
+ struct p9_req_t *req;
+ int id;
- /* free requests associated with tags */
- for (row = 0; row < (c->max_tag/P9_ROW_MAXTAG); row++) {
- for (col = 0; col < P9_ROW_MAXTAG; col++) {
- kfree(c->reqs[row][col].tc);
- kfree(c->reqs[row][col].rc);
- }
- kfree(c->reqs[row]);
+ rcu_read_lock();
+ idr_for_each_entry(&c->reqs, req, id) {
+ pr_info("Tag %d still in use\n", id);
+ p9_free_req(c, req);
}
- c->max_tag = 0;
-}
-
-/**
- * p9_free_req - free a request and clean-up as necessary
- * c: client state
- * r: request to release
- *
- */
-
-static void p9_free_req(struct p9_client *c, struct p9_req_t *r)
-{
- int tag = r->tc->tag;
- p9_debug(P9_DEBUG_MUX, "clnt %p req %p tag: %d\n", c, r, tag);
-
- r->status = REQ_STATUS_IDLE;
- if (tag != P9_NOTAG && p9_idpool_check(tag, c->tagpool))
- p9_idpool_put(tag, c->tagpool);
+ rcu_read_unlock();
}
/**
@@ -698,7 +631,7 @@ static struct p9_req_t *p9_client_prepare_req(struct p9_client *c,
int8_t type, int req_size,
const char *fmt, va_list ap)
{
- int tag, err;
+ int err;
struct p9_req_t *req;
p9_debug(P9_DEBUG_MUX, "client %p op %d\n", c, type);
@@ -711,24 +644,17 @@ static struct p9_req_t *p9_client_prepare_req(struct p9_client *c,
if ((c->status == BeginDisconnect) && (type != P9_TCLUNK))
return ERR_PTR(-EIO);
- tag = P9_NOTAG;
- if (type != P9_TVERSION) {
- tag = p9_idpool_get(c->tagpool);
- if (tag < 0)
- return ERR_PTR(-ENOMEM);
- }
-
- req = p9_tag_alloc(c, tag, req_size);
+ req = p9_tag_alloc(c, type, req_size);
if (IS_ERR(req))
return req;
/* marshall the data */
- p9pdu_prepare(req->tc, tag, type);
+ p9pdu_prepare(req->tc, req->tc->tag, type);
err = p9pdu_vwritef(req->tc, c->proto_version, fmt, ap);
if (err)
goto reterr;
p9pdu_finalize(c, req->tc);
- trace_9p_client_req(c, type, tag);
+ trace_9p_client_req(c, type, req->tc->tag);
return req;
reterr:
p9_free_req(c, req);
@@ -1026,14 +952,11 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
spin_lock_init(&clnt->lock);
idr_init(&clnt->fids);
-
- err = p9_tag_init(clnt);
- if (err < 0)
- goto free_client;
+ idr_init(&clnt->reqs);
err = parse_opts(options, clnt);
if (err < 0)
- goto destroy_tagpool;
+ goto free_client;
if (!clnt->trans_mod)
clnt->trans_mod = v9fs_get_default_trans();
@@ -1042,7 +965,7 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
err = -EPROTONOSUPPORT;
p9_debug(P9_DEBUG_ERROR,
"No transport defined or default transport\n");
- goto destroy_tagpool;
+ goto free_client;
}
p9_debug(P9_DEBUG_MUX, "clnt %p trans %p msize %d protocol %d\n",
@@ -1065,8 +988,6 @@ close_trans:
clnt->trans_mod->close(clnt);
put_trans:
v9fs_put_trans(clnt->trans_mod);
-destroy_tagpool:
- p9_idpool_destroy(clnt->tagpool);
free_client:
kfree(clnt);
return ERR_PTR(err);
@@ -2282,3 +2203,14 @@ error:
return err;
}
EXPORT_SYMBOL(p9_client_readlink);
+
+int __init p9_client_init(void)
+{
+ p9_req_cache = KMEM_CACHE(p9_req_t, 0);
+ return p9_req_cache ? 0 : -ENOMEM;
+}
+
+void __exit p9_client_exit(void)
+{
+ kmem_cache_destroy(p9_req_cache);
+}