[PATCH v3 7/9] IB/mthca: Replace counting semaphore event_sem with wait_event

Binoy Jayan
2016-10-26T08:01:12Z

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/mthca/mthca_cmd.c | 45 ++++++++++++++++++++++-----------
drivers/infiniband/hw/mthca/mthca_dev.h | 3 ++-
2 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/drivers/infiniband/hw/mthca/mthca_cmd.c b/drivers/infiniband/hw/mthca/mthca_cmd.c
index 49c6e19..fab5509 100644
--- a/drivers/infiniband/hw/mthca/mthca_cmd.c
+++ b/drivers/infiniband/hw/mthca/mthca_cmd.c
@@ -405,6 +405,32 @@ void mthca_cmd_event(struct mthca_dev *dev,
complete(&context->done);
}

+static inline struct mthca_cmd_context *
+mthca_try_get_context(struct mthca_cmd *cmd)
+{
+ struct mthca_cmd_context *context = NULL;
+ spin_lock(&cmd->context_lock);
+
+ if (cmd->free_head < 0)
+ goto out;
+
+ context = &cmd->context[cmd->free_head];
+ context->token += cmd->token_mask + 1;
+ cmd->free_head = context->next;
+out:
+ spin_unlock(&cmd->context_lock);
+ return context;
+}
+
+/* wait for and acquire a free context */
+static inline struct mthca_cmd_context *
+mthca_get_free_context(struct mthca_cmd *cmd)
+{
+ struct mthca_cmd_context *context;
+ wait_event(cmd->wq, (context = mthca_try_get_context(cmd)));
+ return context;
+}
+
static int mthca_cmd_wait(struct mthca_dev *dev,
u64 in_param,
u64 *out_param,
@@ -417,15 +443,7 @@ static int mthca_cmd_wait(struct mthca_dev *dev,
int err = 0;
struct mthca_cmd_context *context;

- down(&dev->cmd.event_sem);
-
- spin_lock(&dev->cmd.context_lock);
- BUG_ON(dev->cmd.free_head < 0);
- context = &dev->cmd.context[dev->cmd.free_head];
- context->token += dev->cmd.token_mask + 1;
- dev->cmd.free_head = context->next;
- spin_unlock(&dev->cmd.context_lock);
-
+ context = mthca_get_free_context(&dev->cmd);
init_completion(&context->done);

err = mthca_cmd_post(dev, in_param,
@@ -458,8 +476,8 @@ static int mthca_cmd_wait(struct mthca_dev *dev,
context->next = dev->cmd.free_head;
dev->cmd.free_head = context - dev->cmd.context;
spin_unlock(&dev->cmd.context_lock);
+ wake_up(&dev->cmd.wq);

- up(&dev->cmd.event_sem);
return err;
}

@@ -571,7 +589,7 @@ int mthca_cmd_use_events(struct mthca_dev *dev)
dev->cmd.context[dev->cmd.max_cmds - 1].next = -1;
dev->cmd.free_head = 0;

- sema_init(&dev->cmd.event_sem, dev->cmd.max_cmds);
+ init_waitqueue_head(&dev->cmd.wq);
spin_lock_init(&dev->cmd.context_lock);

for (dev->cmd.token_mask = 1;
@@ -590,12 +608,9 @@ int mthca_cmd_use_events(struct mthca_dev *dev)
*/
void mthca_cmd_use_polling(struct mthca_dev *dev)
{
- int i;
-
dev->cmd.flags &= ~MTHCA_CMD_USE_EVENTS;

- for (i = 0; i < dev->cmd.max_cmds; ++i)
- down(&dev->cmd.event_sem);
+ dev->cmd.free_head = -1;

kfree(dev->cmd.context);
}
diff --git a/drivers/infiniband/hw/mthca/mthca_dev.h b/drivers/infiniband/hw/mthca/mthca_dev.h
index 87ab964..2fc86db 100644
--- a/drivers/infiniband/hw/mthca/mthca_dev.h
+++ b/drivers/infiniband/hw/mthca/mthca_dev.h
@@ -46,6 +46,7 @@
#include <linux/list.h>
#include <linux/semaphore.h>

+#include <rdma/ib_sa.h>
#include "mthca_provider.h"
#include "mthca_doorbell.h"

@@ -121,7 +122,7 @@ struct mthca_cmd {
struct pci_pool *pool;
struct mutex hcr_mutex;
struct mutex poll_mutex;
- struct semaphore event_sem;
+ wait_queue_head_t wq;
int max_cmds;
spinlock_t context_lock;
int free_head;