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Subject[PATCH v2 6/8] IB/hns: Replace counting semaphore event_sem with wait_event
Date
Counting semaphores are going away in the future, so replace the semaphore
mthca_cmd::event_sem with a conditional wait_event.

Signed-off-by: Binoy Jayan <binoy.jayan@linaro.org>
---
drivers/infiniband/hw/hns/hns_roce_cmd.c | 37 +++++++++++++++++++++--------
drivers/infiniband/hw/hns/hns_roce_device.h | 2 +-
2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_cmd.c b/drivers/infiniband/hw/hns/hns_roce_cmd.c
index 51a0675..efc5c48 100644
--- a/drivers/infiniband/hw/hns/hns_roce_cmd.c
+++ b/drivers/infiniband/hw/hns/hns_roce_cmd.c
@@ -189,6 +189,26 @@ void hns_roce_cmd_event(struct hns_roce_dev *hr_dev, u16 token, u8 status,
complete(&context->done);
}

+/* Similar to atomic_cmpxchg but with the complimentary condition. Returns
+ * index to a free node. It also sets cmd->free_head to 'new' so it ensures
+ * atomicity between a call to 'wait_event' and manipulating the free_head.
+ */
+
+static inline int atomic_free_node(struct hns_roce_cmdq *cmd, int new)
+{
+ int orig;
+
+ spin_lock(&cmd->context_lock);
+
+ orig = cmd->free_head;
+ if (likely(cmd->free_head != -1))
+ cmd->free_head = new;
+
+ spin_unlock(&cmd->context_lock);
+
+ return orig;
+}
+
/* this should be called with "use_events" */
static int __hns_roce_cmd_mbox_wait(struct hns_roce_dev *hr_dev, u64 in_param,
u64 out_param, unsigned long in_modifier,
@@ -198,11 +218,12 @@ static int __hns_roce_cmd_mbox_wait(struct hns_roce_dev *hr_dev, u64 in_param,
struct hns_roce_cmdq *cmd = &hr_dev->cmd;
struct device *dev = &hr_dev->pdev->dev;
struct hns_roce_cmd_context *context;
- int ret = 0;
+ int orig_free_head, ret = 0;
+
+ wait_event(cmd->wq, (orig_free_head = atomic_free_node(cmd, -1)) != -1);

spin_lock(&cmd->context_lock);
- WARN_ON(cmd->free_head < 0);
- context = &cmd->context[cmd->free_head];
+ context = &cmd->context[orig_free_head];
context->token += cmd->token_mask + 1;
cmd->free_head = context->next;
spin_unlock(&cmd->context_lock);
@@ -238,6 +259,7 @@ static int __hns_roce_cmd_mbox_wait(struct hns_roce_dev *hr_dev, u64 in_param,
context->next = cmd->free_head;
cmd->free_head = context - cmd->context;
spin_unlock(&cmd->context_lock);
+ wake_up(&cmd->wq);

return ret;
}
@@ -248,10 +270,8 @@ static int hns_roce_cmd_mbox_wait(struct hns_roce_dev *hr_dev, u64 in_param,
{
int ret = 0;

- down(&hr_dev->cmd.event_sem);
ret = __hns_roce_cmd_mbox_wait(hr_dev, in_param, out_param,
in_modifier, op_modifier, op, timeout);
- up(&hr_dev->cmd.event_sem);

return ret;
}
@@ -313,7 +333,7 @@ int hns_roce_cmd_use_events(struct hns_roce_dev *hr_dev)
hr_cmd->context[hr_cmd->max_cmds - 1].next = -1;
hr_cmd->free_head = 0;

- sema_init(&hr_cmd->event_sem, hr_cmd->max_cmds);
+ init_waitqueue_head(&hr_cmd->wq);
spin_lock_init(&hr_cmd->context_lock);

hr_cmd->token_mask = CMD_TOKEN_MASK;
@@ -325,12 +345,9 @@ int hns_roce_cmd_use_events(struct hns_roce_dev *hr_dev)
void hns_roce_cmd_use_polling(struct hns_roce_dev *hr_dev)
{
struct hns_roce_cmdq *hr_cmd = &hr_dev->cmd;
- int i;

hr_cmd->use_events = 0;
-
- for (i = 0; i < hr_cmd->max_cmds; ++i)
- down(&hr_cmd->event_sem);
+ hr_cmd->free_head = -1;

kfree(hr_cmd->context);
}
diff --git a/drivers/infiniband/hw/hns/hns_roce_device.h b/drivers/infiniband/hw/hns/hns_roce_device.h
index 2afe075..ac95f52 100644
--- a/drivers/infiniband/hw/hns/hns_roce_device.h
+++ b/drivers/infiniband/hw/hns/hns_roce_device.h
@@ -364,7 +364,7 @@ struct hns_roce_cmdq {
* Event mode: cmd register mutex protection,
* ensure to not exceed max_cmds and user use limit region
*/
- struct semaphore event_sem;
+ wait_queue_head_t wq;
int max_cmds;
spinlock_t context_lock;
int free_head;
--
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a Linux Foundation Collaborative Project
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