net/sctp: Replace in/out stream arrays with flex_array

This path replaces physically contiguous memory arrays
allocated using kmalloc_array() with flexible arrays.
This enables to avoid memory allocation failures on the
systems under a memory stress.

Signed-off-by: Oleg Babin <obabin@virtuozzo.com>
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 6b2b8df..28a7c8e 100644 (file)
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -57,6 +57,7 @@
 #include <linux/atomic.h>              /* This gets us atomic counters.  */
 #include <linux/skbuff.h>      /* We need sk_buff_head. */
 #include <linux/workqueue.h>   /* We need tq_struct.    */
+#include <linux/flex_array.h>  /* We need flex_array.   */
 #include <linux/sctp.h>                /* We need sctp* header structs.  */
 #include <net/sctp/auth.h>     /* We need auth specific structs */
 #include <net/ip.h>            /* For inet_skb_parm */
@@ -1438,8 +1439,8 @@ struct sctp_stream_in {
 };
 
 struct sctp_stream {
-       struct sctp_stream_out *out;
-       struct sctp_stream_in *in;
+       struct flex_array *out;
+       struct flex_array *in;
        __u16 outcnt;
        __u16 incnt;
        /* Current stream being sent, if any */
@@ -1465,14 +1466,14 @@ static inline struct sctp_stream_out *sctp_stream_out(
        const struct sctp_stream *stream,
        __u16 sid)
 {
-       return ((struct sctp_stream_out *)(stream->out)) + sid;
+       return flex_array_get(stream->out, sid);
 }
 
 static inline struct sctp_stream_in *sctp_stream_in(
        const struct sctp_stream *stream,
        __u16 sid)
 {
-       return ((struct sctp_stream_in *)(stream->in)) + sid;
+       return flex_array_get(stream->in, sid);
 }
 
 #define SCTP_SO(s, i) sctp_stream_out((s), (i))

diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index 7ca6fe4..ffb940d 100644 (file)
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -37,6 +37,53 @@
 #include <net/sctp/sm.h>
 #include <net/sctp/stream_sched.h>
 
+static struct flex_array *fa_alloc(size_t elem_size, size_t elem_count,
+                                  gfp_t gfp)
+{
+       struct flex_array *result;
+       int err;
+
+       result = flex_array_alloc(elem_size, elem_count, gfp);
+       if (result) {
+               err = flex_array_prealloc(result, 0, elem_count, gfp);
+               if (err) {
+                       flex_array_free(result);
+                       result = NULL;
+               }
+       }
+
+       return result;
+}
+
+static void fa_free(struct flex_array *fa)
+{
+       if (fa)
+               flex_array_free(fa);
+}
+
+static void fa_copy(struct flex_array *fa, struct flex_array *from,
+                   size_t index, size_t count)
+{
+       void *elem;
+
+       while (count--) {
+               elem = flex_array_get(from, index);
+               flex_array_put(fa, index, elem, 0);
+               index++;
+       }
+}
+
+static void fa_zero(struct flex_array *fa, size_t index, size_t count)
+{
+       void *elem;
+
+       while (count--) {
+               elem = flex_array_get(fa, index);
+               memset(elem, 0, fa->element_size);
+               index++;
+       }
+}
+
 /* Migrates chunks from stream queues to new stream queues if needed,
  * but not across associations. Also, removes those chunks to streams
  * higher than the new max.
@@ -78,34 +125,33 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream,
                 * sctp_stream_update will swap ->out pointers.
                 */
                for (i = 0; i < outcnt; i++) {
-                       kfree(new->out[i].ext);
-                       new->out[i].ext = stream->out[i].ext;
-                       stream->out[i].ext = NULL;
+                       kfree(SCTP_SO(new, i)->ext);
+                       SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext;
+                       SCTP_SO(stream, i)->ext = NULL;
                }
        }
 
        for (i = outcnt; i < stream->outcnt; i++)
-               kfree(stream->out[i].ext);
+               kfree(SCTP_SO(stream, i)->ext);
 }
 
 static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
                                 gfp_t gfp)
 {
-       struct sctp_stream_out *out;
+       struct flex_array *out;
+       size_t elem_size = sizeof(struct sctp_stream_out);
 
-       out = kmalloc_array(outcnt, sizeof(*out), gfp);
+       out = fa_alloc(elem_size, outcnt, gfp);
        if (!out)
                return -ENOMEM;
 
        if (stream->out) {
-               memcpy(out, stream->out, min(outcnt, stream->outcnt) *
-                                        sizeof(*out));
-               kfree(stream->out);
+               fa_copy(out, stream->out, 0, min(outcnt, stream->outcnt));
+               fa_free(stream->out);
        }
 
        if (outcnt > stream->outcnt)
-               memset(out + stream->outcnt, 0,
-                      (outcnt - stream->outcnt) * sizeof(*out));
+               fa_zero(out, stream->outcnt, (outcnt - stream->outcnt));
 
        stream->out = out;
 
@@ -115,22 +161,20 @@ static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
 static int sctp_stream_alloc_in(struct sctp_stream *stream, __u16 incnt,
                                gfp_t gfp)
 {
-       struct sctp_stream_in *in;
-
-       in = kmalloc_array(incnt, sizeof(*stream->in), gfp);
+       struct flex_array *in;
+       size_t elem_size = sizeof(struct sctp_stream_in);
 
+       in = fa_alloc(elem_size, incnt, gfp);
        if (!in)
                return -ENOMEM;
 
        if (stream->in) {
-               memcpy(in, stream->in, min(incnt, stream->incnt) *
-                                      sizeof(*in));
-               kfree(stream->in);
+               fa_copy(in, stream->in, 0, min(incnt, stream->incnt));
+               fa_free(stream->in);
        }
 
        if (incnt > stream->incnt)
-               memset(in + stream->incnt, 0,
-                      (incnt - stream->incnt) * sizeof(*in));
+               fa_zero(in, stream->incnt, (incnt - stream->incnt));
 
        stream->in = in;
 
@@ -174,7 +218,7 @@ in:
        ret = sctp_stream_alloc_in(stream, incnt, gfp);
        if (ret) {
                sched->free(stream);
-               kfree(stream->out);
+               fa_free(stream->out);
                stream->out = NULL;
                stream->outcnt = 0;
                goto out;
@@ -206,8 +250,8 @@ void sctp_stream_free(struct sctp_stream *stream)
        sched->free(stream);
        for (i = 0; i < stream->outcnt; i++)
                kfree(SCTP_SO(stream, i)->ext);
-       kfree(stream->out);
-       kfree(stream->in);
+       fa_free(stream->out);
+       fa_free(stream->in);
 }
 
 void sctp_stream_clear(struct sctp_stream *stream)