[PATCH] IB: Add user-supplied context to userspace CM ABI

- Add user specified context to all uCM events.  Users will not retrieve
  any events associated with the context after destroying the corresponding
  cm_id.
- Provide the ib_cm_init_qp_attr() call to userspace clients of the CM.
  This call may be used to set QP attributes properly before modifying the QP.
- Fixes some error handling synchonization and cleanup issues.
- Performs some minor code cleanup.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

3 files changed, 261 insertions, 109 deletions

diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c
index 79595826ccc7..d0f0b0a2edd3 100644
--- a/drivers/infiniband/core/ucm.c
+++ b/drivers/infiniband/core/ucm.c
@@ -72,7 +72,6 @@ enum {
 
 static struct semaphore ctx_id_mutex;
 static struct idr       ctx_id_table;
-static int              ctx_id_rover = 0;
 
 static struct ib_ucm_context *ib_ucm_ctx_get(struct ib_ucm_file *file, int id)
 {
@@ -97,33 +96,16 @@ static void ib_ucm_ctx_put(struct ib_ucm_context *ctx)
                 wake_up(&ctx->wait);
 }
 
-static ssize_t ib_ucm_destroy_ctx(struct ib_ucm_file *file, int id)
+static inline int ib_ucm_new_cm_id(int event)
 {
-        struct ib_ucm_context *ctx;
-        struct ib_ucm_event *uevent;
-
-        down(&ctx_id_mutex);
-        ctx = idr_find(&ctx_id_table, id);
-        if (!ctx)
-                ctx = ERR_PTR(-ENOENT);
-        else if (ctx->file != file)
-                ctx = ERR_PTR(-EINVAL);
-        else
-                idr_remove(&ctx_id_table, ctx->id);
-        up(&ctx_id_mutex);
-
-        if (IS_ERR(ctx))
-                return PTR_ERR(ctx);
-
-        atomic_dec(&ctx->ref);
-        wait_event(ctx->wait, !atomic_read(&ctx->ref));
+        return event == IB_CM_REQ_RECEIVED || event == IB_CM_SIDR_REQ_RECEIVED;
+}
 
-        /* No new events will be generated after destroying the cm_id. */
-        if (!IS_ERR(ctx->cm_id))
-                ib_destroy_cm_id(ctx->cm_id);
+static void ib_ucm_cleanup_events(struct ib_ucm_context *ctx)
+{
+        struct ib_ucm_event *uevent;
 
-        /* Cleanup events not yet reported to the user. */
-        down(&file->mutex);
+        down(&ctx->file->mutex);
         list_del(&ctx->file_list);
         while (!list_empty(&ctx->events)) {
 
@@ -133,15 +115,12 @@ static ssize_t ib_ucm_destroy_ctx(struct ib_ucm_file *file, int id)
                 list_del(&uevent->ctx_list);
 
                 /* clear incoming connections. */
-                if (uevent->cm_id)
+                if (ib_ucm_new_cm_id(uevent->resp.event))
                         ib_destroy_cm_id(uevent->cm_id);
 
                 kfree(uevent);
         }
-        up(&file->mutex);
-
-        kfree(ctx);
-        return 0;
+        up(&ctx->file->mutex);
 }
 
 static struct ib_ucm_context *ib_ucm_ctx_alloc(struct ib_ucm_file *file)
@@ -153,36 +132,31 @@ static struct ib_ucm_context *ib_ucm_ctx_alloc(struct ib_ucm_file *file)
         if (!ctx)
                 return NULL;
 
+        memset(ctx, 0, sizeof *ctx);
         atomic_set(&ctx->ref, 1);
         init_waitqueue_head(&ctx->wait);
         ctx->file = file;
-
         INIT_LIST_HEAD(&ctx->events);
 
-        list_add_tail(&ctx->file_list, &file->ctxs);
-
-        ctx_id_rover = (ctx_id_rover + 1) & INT_MAX;
-retry:
-        result = idr_pre_get(&ctx_id_table, GFP_KERNEL);
-        if (!result)
-                goto error;
+        do {
+                result = idr_pre_get(&ctx_id_table, GFP_KERNEL);
+                if (!result)
+                        goto error;
 
-        down(&ctx_id_mutex);
-        result = idr_get_new_above(&ctx_id_table, ctx, ctx_id_rover, &ctx->id);
-        up(&ctx_id_mutex);
+                down(&ctx_id_mutex);
+                result = idr_get_new(&ctx_id_table, ctx, &ctx->id);
+                up(&ctx_id_mutex);
+        } while (result == -EAGAIN);
 
-        if (result == -EAGAIN)
-                goto retry;
         if (result)
                 goto error;
 
+        list_add_tail(&ctx->file_list, &file->ctxs);
         ucm_dbg("Allocated CM ID <%d>\n", ctx->id);
-
         return ctx;
+
 error:
-        list_del(&ctx->file_list);
         kfree(ctx);
-
         return NULL;
 }
 /*
@@ -219,12 +193,9 @@ static void ib_ucm_event_path_get(struct ib_ucm_path_rec *upath,
                 kpath->packet_life_time_selector;
 }
 
-static void ib_ucm_event_req_get(struct ib_ucm_context *ctx,
-                                 struct ib_ucm_req_event_resp *ureq,
+static void ib_ucm_event_req_get(struct ib_ucm_req_event_resp *ureq,
                                  struct ib_cm_req_event_param *kreq)
 {
-        ureq->listen_id = ctx->id;
-
         ureq->remote_ca_guid             = kreq->remote_ca_guid;
         ureq->remote_qkey                = kreq->remote_qkey;
         ureq->remote_qpn                 = kreq->remote_qpn;
@@ -259,14 +230,6 @@ static void ib_ucm_event_rep_get(struct ib_ucm_rep_event_resp *urep,
         urep->srq                 = krep->srq;
 }
 
-static void ib_ucm_event_sidr_req_get(struct ib_ucm_context *ctx,
-                                      struct ib_ucm_sidr_req_event_resp *ureq,
-                                      struct ib_cm_sidr_req_event_param *kreq)
-{
-        ureq->listen_id = ctx->id;
-        ureq->pkey      = kreq->pkey;
-}
-
 static void ib_ucm_event_sidr_rep_get(struct ib_ucm_sidr_rep_event_resp *urep,
                                       struct ib_cm_sidr_rep_event_param *krep)
 {
@@ -275,15 +238,14 @@ static void ib_ucm_event_sidr_rep_get(struct ib_ucm_sidr_rep_event_resp *urep,
         urep->qpn    = krep->qpn;
 };
 
-static int ib_ucm_event_process(struct ib_ucm_context *ctx,
-                                struct ib_cm_event *evt,
+static int ib_ucm_event_process(struct ib_cm_event *evt,
                                 struct ib_ucm_event *uvt)
 {
         void *info = NULL;
 
         switch (evt->event) {
         case IB_CM_REQ_RECEIVED:
-                ib_ucm_event_req_get(ctx, &uvt->resp.u.req_resp,
+                ib_ucm_event_req_get(&uvt->resp.u.req_resp,