[SPARC64]: Fix race between MD update and dr-cpu add.

We need to make sure the MD update occurs before we try to
process dr-cpu configure requests.  MD update and dr-cpu
were being processed by seperate threads so that did not
happen occaisionally.

Fix this by executing all domain services data packets from
a single thread, in order.

This will help simplify some other things as well.

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 147 insertions, 143 deletions

diff --git a/arch/sparc64/kernel/ds.c b/arch/sparc64/kernel/ds.c
index 1c587107cef0..ba01533f4e03 100644
--- a/arch/sparc64/kernel/ds.c
+++ b/arch/sparc64/kernel/ds.c
@@ -228,7 +228,7 @@ static struct ds_cap_state *find_cap_by_string(const char *name)
         return NULL;
 }
 
-static int ds_send(struct ldc_channel *lp, void *data, int len)
+static int __ds_send(struct ldc_channel *lp, void *data, int len)
 {
         int err, limit = 1000;
 
@@ -243,6 +243,18 @@ static int ds_send(struct ldc_channel *lp, void *data, int len)
         return err;
 }
 
+static int ds_send(struct ldc_channel *lp, void *data, int len)
+{
+        unsigned long flags;
+        int err;
+
+        spin_lock_irqsave(&ds_lock, flags);
+        err = __ds_send(lp, data, len);
+        spin_unlock_irqrestore(&ds_lock, flags);
+
+        return err;
+}
+
 struct ds_md_update_req {
         __u64                           req_num;
 };
@@ -267,6 +279,8 @@ static void md_update_data(struct ldc_channel *lp,
 
         printk(KERN_INFO PFX "Machine description update.\n");
 
+        mdesc_update();
+
         memset(&pkt, 0, sizeof(pkt));
         pkt.data.tag.type = DS_DATA;
         pkt.data.tag.len = sizeof(pkt) - sizeof(struct ds_msg_tag);
@@ -275,8 +289,6 @@ static void md_update_data(struct ldc_channel *lp,
         pkt.res.result = DS_OK;
 
         ds_send(lp, &pkt, sizeof(pkt));
-
-        mdesc_update();
 }
 
 struct ds_shutdown_req {
@@ -391,18 +403,6 @@ struct dr_cpu_resp_entry {
         __u32                           str_off;
 };
 
-/* DR cpu requests get queued onto the work list by the
- * dr_cpu_data() callback.  The list is protected by
- * ds_lock, and processed by dr_cpu_process() in order.
- */
-static LIST_HEAD(dr_cpu_work_list);
-static DECLARE_WAIT_QUEUE_HEAD(dr_cpu_wait);
-
-struct dr_cpu_queue_entry {
-        struct list_head                list;
-        char                            req[0];
-};
-
 static void __dr_cpu_send_error(struct ds_cap_state *cp, struct ds_data *data)
 {
         struct dr_cpu_tag *tag = (struct dr_cpu_tag *) (data + 1);
@@ -425,7 +425,7 @@ static void __dr_cpu_send_error(struct ds_cap_state *cp, struct ds_data *data)
 
         pkt.data.tag.len = msg_len - sizeof(struct ds_msg_tag);
 
-        ds_send(dp->lp, &pkt, msg_len);
+        __ds_send(dp->lp, &pkt, msg_len);
 }
 
 static void dr_cpu_send_error(struct ds_cap_state *cp, struct ds_data *data)
@@ -555,7 +555,7 @@ static int dr_cpu_configure(struct ds_cap_state *cp, u64 req_num,
         }
 
         spin_lock_irqsave(&ds_lock, flags);
-        ds_send(ds_info->lp, resp, resp_len);
+        __ds_send(ds_info->lp, resp, resp_len);
         spin_unlock_irqrestore(&ds_lock, flags);
 
         kfree(resp);
@@ -596,7 +596,7 @@ static int dr_cpu_unconfigure(struct ds_cap_state *cp, u64 req_num,
         }
 
         spin_lock_irqsave(&ds_lock, flags);
-        ds_send(ds_info->lp, resp, resp_len);
+        __ds_send(ds_info->lp, resp, resp_len);
         spin_unlock_irqrestore(&ds_lock, flags);
 
         kfree(resp);
@@ -604,107 +604,49 @@ static int dr_cpu_unconfigure(struct ds_cap_state *cp, u64 req_num,
         return 0;
 }
 
-static void process_dr_cpu_list(struct ds_cap_state *cp)
+static void dr_cpu_data(struct ldc_channel *lp,
+                        struct ds_cap_state *cp,
+                        void *buf, int len)
 {
-        struct dr_cpu_queue_entry *qp, *tmp;
-        unsigned long flags;
-        LIST_HEAD(todo);
+        struct ds_data *data = buf;
+        struct dr_cpu_tag *tag = (struct dr_cpu_tag *) (data + 1);
+        u32 *cpu_list = (u32 *) (tag + 1);
+        u64 req_num = tag->req_num;
         cpumask_t mask;
+        unsigned int i;
+        int err;
 
-        spin_lock_irqsave(&ds_lock, flags);
-        list_splice(&dr_cpu_work_list, &todo);
-        INIT_LIST_HEAD(&dr_cpu_work_list);
-        spin_unlock_irqrestore(&ds_lock, flags);
-
-        list_for_each_entry_safe(qp, tmp, &todo, list) {
-                struct ds_data *data = (struct ds_data *) qp->req;
-                struct dr_cpu_tag *tag = (struct dr_cpu_tag *) (data + 1);
-                u32 *cpu_list = (u32 *) (tag + 1);
-                u64 req_num = tag->req_num;
-                unsigned int i;
-                int err;
-
-                switch (tag->type) {
-                case DR_CPU_CONFIGURE:
-                case DR_CPU_UNCONFIGURE:
-                case DR_CPU_FORCE_UNCONFIGURE:
-                        break;
-
-                default:
-                        dr_cpu_send_error(cp, data);
-                        goto next;
-                }
-
-                purge_dups(cpu_list, tag->num_records);
-
-                cpus_clear(mask);
-                for (i = 0; i < tag->num_records; i++) {
-                        if (cpu_list[i] == CPU_SENTINEL)
-                                continue;
-
-                        if (cpu_list[i] < NR_CPUS)
-                                cpu_set(cpu_list[i], mask);
-                }
-
-                if (tag->type == DR_CPU_CONFIGURE)
-                        err = dr_cpu_configure(cp, req_num, &mask);
-                else
-                        err = dr_cpu_unconfigure(cp, req_num, &mask);
-
-                if (err)
-                        dr_cpu_send_error(cp, data);
+        switch (tag->type) {
+        case DR_CPU_CONFIGURE:
+        case DR_CPU_UNCONFIGURE:
+        case DR_CPU_FORCE_UNCONFIGURE:
+                break;
 
-next:
-                list_del(&qp->list);
-                kfree(qp);
+        default:
+                dr_cpu_send_error(cp, data);
+                return;
         }
-}
 
-static int dr_cpu_thread(void *__unused)
-{
-        struct ds_cap_state *cp;
-        DEFINE_WAIT(wait);
+        purge_dups(cpu_list, tag->num_records);
 
-        cp = find_cap_by_string("dr-cpu");
-
-        while (1) {
-                prepare_to_wait(&dr_cpu_wait, &wait, TASK_INTERRUPTIBLE);
-                if (list_empty(&dr_cpu_work_list))
-                        schedule();
-                finish_wait(&dr_cpu_wait, &wait);
-
-                if (kthread_should_stop())
-                        break;
+        cpus_clear(mask);
+        for (i = 0; i < tag->num_records; i++) {
+                if (cpu_list[i] == CPU_SENTINEL)
+                        continue;
 
-                process_dr_cpu_list(cp);
+                if (cpu_list[i] < NR_CPUS)
+                        cpu_set(cpu_list[i], mask);
         }
 
-        return 0;
-}
-
-static void dr_cpu_data(struct ldc_channel *lp,
-                        struct ds_cap_state *dp,
-                        void *buf, int len)
-{
-        struct dr_cpu_queue_entry *qp;
-        struct ds_data *dpkt = buf;
-        struct dr_cpu_tag *rp;
+        if (tag->type == DR_CPU_CONFIGURE)
+                err = dr_cpu_configure(cp, req_num, &mask);
+        else
+                err = dr_cpu_unconfigure(cp, req_num, &mask);
 
-        rp = (struct dr_cpu_tag *) (dpkt + 1);
-
-        qp = kmalloc(sizeof(struct dr_cpu_queue_entry) + len, GFP_ATOMIC);
-        if (!qp) {
-                struct ds_cap_state *cp;
-
-                cp = find_cap_by_string("dr-cpu");
-                __dr_cpu_send_error(cp, dpkt);
-        } else {
-                memcpy(&qp->req, buf, len);
-                list_add_tail(&qp->list, &dr_cpu_work_list);
-                wake_up(&dr_cpu_wait);
-        }
+        if (err)
+                dr_cpu_send_error(cp, data);
 }
-#endif
+#endif /* CONFIG_HOTPLUG_CPU */
 
 struct ds_pri_msg {
         __u64                           req_num;
@@ -820,7 +762,7 @@ void ldom_set_var(const char *var, const char *value)
                 ds_var_doorbell = 0;
                 ds_var_response = -1;
 
-                ds_send(dp->lp, &pkt, msg_len);
+                __ds_send(dp->lp, &pkt, msg_len);
                 spin_unlock_irqrestore(&ds_lock, flags);
 
                 loops = 1000;
@@ -904,7 +846,7 @@ static int register_services(struct ds_info *dp)
                 pbuf.req.minor = 0;
                 strcpy(pbuf.req.svc_id, cp->service_id);
 
-                err = ds_send(lp, &pbuf, msg_len);
+                err = __ds_send(lp, &pbuf, msg_len);
                 if (err > 0)
                         cp->state = CAP_STATE_REG_SENT;
         }
@@ -960,27 +902,97 @@ conn_reset:
         return -ECONNRESET;
 }
 
+static void __send_ds_nack(struct ds_info *dp, u64 handle)
+{
+        struct ds_data_nack nack = {
+                .tag = {
+                        .type = DS_NACK,
+                        .len = (sizeof(struct ds_data_nack) -
+                                sizeof(struct ds_msg_tag)),
+                },
+                .handle = handle,
+                .result = DS_INV_HDL,
+        };
+
+        __ds_send(dp->lp, &nack, sizeof(nack));
+}
+
+static LIST_HEAD(ds_work_list);
+static DECLARE_WAIT_QUEUE_HEAD(ds_wait);
+
+struct ds_queue_entry {
+        struct list_head                list;
+        int                             req_len;
+        int                             __pad;
+        u64                             req[0];
+};
+
+static void process_ds_work(void)
+{
+        struct ds_queue_entry *qp, *tmp;
+        static struct ds_info *dp;
+        unsigned long flags;
+        LIST_HEAD(todo);
+
+        spin_lock_irqsave(&ds_lock, flags);
+        list_splice(&ds_work_list, &todo);
+        INIT_LIST_HEAD(&ds_work_list);
+        spin_unlock_irqrestore(&ds_lock, flags);
+
+        dp = ds_info;
+
+        list_for_each_entry_safe(qp, tmp, &todo, list) {
+                struct ds_data *dpkt = (struct ds_data *) qp->req;
+                struct ds_cap_state *cp = find_cap(dpkt->handle);
+                int req_len = qp->req_len;
+
+                if (!cp) {
+                        printk(KERN_ERR PFX "Data for unknown handle %lu\n",
+                               dpkt->handle);
+
+                        spin_lock_irqsave(&ds_lock, flags);
+                        __send_ds_nack(dp, dpkt->handle);
+                        spin_unlock_irqrestore(&ds_lock, flags);
+                } else {
+                        cp->data(dp->lp, cp, dpkt, req_len);
+                }
+
+                list_del(&qp->list);
+                kfree(qp);
+        }
+}
+
+static int ds_thread(void *__unused)
+{
+        DEFINE_WAIT(wait);
+
+        while (1) {
+                prepare_to_wait(&ds_wait, &wait, TASK_INTERRUPTIBLE);
+                if (list_empty(&ds_work_list))
+                        schedule();
+                finish_wait(&ds_wait, &wait);
+
+                if (kthread_should_stop())
+                        break;
+
+                process_ds_work();
+        }
+
+        return 0;
+}
+
 static int ds_data(struct ds_info *dp, struct ds_msg_tag *pkt, int len)
 {
         struct ds_data *dpkt = (struct ds_data *) pkt;
-        struct ds_cap_state *cp = find_cap(dpkt->handle);
-
-        if (!cp) {
-                struct ds_data_nack nack = {
-                        .tag = {
-                                .type = DS_NACK,
-                                .len = (sizeof(struct ds_data_nack) -
-                                        sizeof(struct ds_msg_tag)),
-                        },
-                        .handle = dpkt->handle,
-                        .result = DS_INV_HDL,
-                };
-
-                printk(KERN_ERR PFX "Data for unknown handle %lu\n",
-                       dpkt->handle);
-                ds_send(dp->lp, &nack, sizeof(nack));
+        struct ds_queue_entry *qp;
+
+        qp = kmalloc(sizeof(struct ds_queue_entry) + len, GFP_ATOMIC);
+        if (!qp) {
+                __send_ds_nack(dp, dpkt->handle);
         } else {
-                cp->data(dp->lp, cp, dpkt, len);
+                memcpy(&qp->req, pkt, len);
+                list_add_tail(&qp->list, &ds_work_list);
+                wake_up(&ds_wait);
         }
         return 0;
 }
@@ -996,7 +1008,7 @@ static void ds_up(struct ds_info *dp)
         req.ver.major = 1;
         req.ver.minor = 0;
 
-        err = ds_send(lp, &req, sizeof(req));
+        err = __ds_send(lp, &req, sizeof(req));
         if (err > 0)
                 dp->hs_state = DS_HS_START;
 }
@@ -1148,9 +1160,7 @@ static int __init ds_init(void)
         for (i = 0; i < ARRAY_SIZE(ds_states); i++)
                 ds_states[i].handle = ((u64)i << 32);
 
-#ifdef CONFIG_HOTPLUG_CPU
-        kthread_run(dr_cpu_thread, NULL, "kdrcpud");
-#endif
+        kthread_run(ds_thread, NULL, "kldomd");
 
         return vio_register_driver(&ds_driver);
 }
diff --git a/arch/sparc64/kernel/mdesc.c b/arch/sparc64/kernel/mdesc.c
index 62a389793949..de5310ffdb48 100644
--- a/arch/sparc64/kernel/mdesc.c
+++ b/arch/sparc64/kernel/mdesc.c
@@ -214,7 +214,7 @@ void mdesc_release(struct mdesc_handle *hp)
 }
 EXPORT_SYMBOL(mdesc_release);
 
-static void do_mdesc_update(struct work_struct *work)
+void mdesc_update(void)
 {
         unsigned long len, real_len, status;
         struct mdesc_handle *hp, *orig_hp;
@@ -248,13 +248,6 @@ static void do_mdesc_update(struct work_struct *work)
         spin_unlock_irqrestore(&mdesc_lock, flags);
 }
 
-static DECLARE_WORK(mdesc_update_work, do_mdesc_update);
-
-void mdesc_update(void)
-{
-        schedule_work(&mdesc_update_work);
-}
-
 static struct mdesc_elem *node_block(struct mdesc_hdr *mdesc)
 {
         return (struct mdesc_elem *) (mdesc + 1);
@@ -278,13 +271,14 @@ u64 mdesc_node_by_name(struct mdesc_handle *hp,
         u64 last_node = hp->mdesc.node_sz / 16;
         u64 ret;
 
-        if (from_node == MDESC_NODE_NULL)
-                from_node = 0;
-
-        if (from_node >= last_node)
+        if (from_node == MDESC_NODE_NULL) {
+                ret = from_node = 0;
+        } else if (from_node >= last_node) {
                 return MDESC_NODE_NULL;
+        } else {
+                ret = ep[from_node].d.val;
+        }
 
-        ret = ep[from_node].d.val;
         while (ret < last_node) {
                 if (ep[ret].tag != MD_NODE)
                         return MDESC_NODE_NULL;