The function can be used to retrieve and clear/remove a transation ID
from a channel requestor, provided the memory address corresponding to
the ID equals a specified address. The function, and its 'lockless'
variant __vmbus_request_addr_match(), will be used by hv_pci.
Refactor vmbus_request_addr() to reuse the 'newly' introduced code.
No functional change.
Suggested-by: Michael Kelley <[email protected]>
Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
---
drivers/hv/channel.c | 65 ++++++++++++++++++++++++++++++------------
include/linux/hyperv.h | 5 ++++
2 files changed, 52 insertions(+), 18 deletions(-)
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 585a8084848bf..49f10a603a091 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -1279,17 +1279,11 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
}
EXPORT_SYMBOL_GPL(vmbus_next_request_id);
-/*
- * vmbus_request_addr - Returns the memory address stored at @trans_id
- * in @rqstor. Uses a spin lock to avoid race conditions.
- * @channel: Pointer to the VMbus channel struct
- * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
- * next request id.
- */
-u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
+/* As in vmbus_request_addr_match() but without the requestor lock */
+u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
+ u64 rqst_addr)
{
struct vmbus_requestor *rqstor = &channel->requestor;
- unsigned long flags;
u64 req_addr;
/* Check rqstor has been initialized */
@@ -1300,25 +1294,60 @@ u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
if (!trans_id)
return VMBUS_RQST_ERROR;
- spin_lock_irqsave(&rqstor->req_lock, flags);
-
/* Data corresponding to trans_id is stored at trans_id - 1 */
trans_id--;
/* Invalid trans_id */
- if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {
- spin_unlock_irqrestore(&rqstor->req_lock, flags);
+ if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap))
return VMBUS_RQST_ERROR;
- }
req_addr = rqstor->req_arr[trans_id];
- rqstor->req_arr[trans_id] = rqstor->next_request_id;
- rqstor->next_request_id = trans_id;
+ if (rqst_addr == VMBUS_RQST_ADDR_ANY || req_addr == rqst_addr) {
+ rqstor->req_arr[trans_id] = rqstor->next_request_id;
+ rqstor->next_request_id = trans_id;
- /* The already held spin lock provides atomicity */
- bitmap_clear(rqstor->req_bitmap, trans_id, 1);
+ /* The already held spin lock provides atomicity */
+ bitmap_clear(rqstor->req_bitmap, trans_id, 1);
+ }
+
+ return req_addr;
+}
+EXPORT_SYMBOL_GPL(__vmbus_request_addr_match);
+
+/*
+ * vmbus_request_addr_match - Clears/removes @trans_id from the @channel's
+ * requestor, provided the memory address stored at @trans_id equals @rqst_addr
+ * (or provided @rqst_addr matches the sentinel value VMBUS_RQST_ADDR_ANY).
+ *
+ * Returns the memory address stored at @trans_id, or VMBUS_RQST_ERROR if
+ * @trans_id is not contained in the requestor.
+ *
+ * Acquires and releases the requestor spin lock.
+ */
+u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
+ u64 rqst_addr)
+{
+ struct vmbus_requestor *rqstor = &channel->requestor;
+ unsigned long flags;
+ u64 req_addr;
+ spin_lock_irqsave(&rqstor->req_lock, flags);
+ req_addr = __vmbus_request_addr_match(channel, trans_id, rqst_addr);
spin_unlock_irqrestore(&rqstor->req_lock, flags);
+
return req_addr;
}
+EXPORT_SYMBOL_GPL(vmbus_request_addr_match);
+
+/*
+ * vmbus_request_addr - Returns the memory address stored at @trans_id
+ * in @rqstor. Uses a spin lock to avoid race conditions.
+ * @channel: Pointer to the VMbus channel struct
+ * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
+ * next request id.
+ */
+u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
+{
+ return vmbus_request_addr_match(channel, trans_id, VMBUS_RQST_ADDR_ANY);
+}
EXPORT_SYMBOL_GPL(vmbus_request_addr);
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index a7cb596d893b1..c77d78f34b96a 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -788,6 +788,7 @@ struct vmbus_requestor {
#define VMBUS_NO_RQSTOR U64_MAX
#define VMBUS_RQST_ERROR (U64_MAX - 1)
+#define VMBUS_RQST_ADDR_ANY U64_MAX
/* NetVSC-specific */
#define VMBUS_RQST_ID_NO_RESPONSE (U64_MAX - 2)
/* StorVSC-specific */
@@ -1042,6 +1043,10 @@ struct vmbus_channel {
};
u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr);
+u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
+ u64 rqst_addr);
+u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
+ u64 rqst_addr);
u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id);
static inline bool is_hvsock_channel(const struct vmbus_channel *c)
--
2.25.1
From: Andrea Parri (Microsoft) <[email protected]> Sent: Tuesday, April 19, 2022 5:23 AM
>
> The function can be used to retrieve and clear/remove a transation ID
> from a channel requestor, provided the memory address corresponding to
> the ID equals a specified address. The function, and its 'lockless'
> variant __vmbus_request_addr_match(), will be used by hv_pci.
>
> Refactor vmbus_request_addr() to reuse the 'newly' introduced code.
>
> No functional change.
>
> Suggested-by: Michael Kelley <[email protected]>
> Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
> ---
> drivers/hv/channel.c | 65 ++++++++++++++++++++++++++++++------------
> include/linux/hyperv.h | 5 ++++
> 2 files changed, 52 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
> index 585a8084848bf..49f10a603a091 100644
> --- a/drivers/hv/channel.c
> +++ b/drivers/hv/channel.c
> @@ -1279,17 +1279,11 @@ u64 vmbus_next_request_id(struct vmbus_channel
> *channel, u64 rqst_addr)
> }
> EXPORT_SYMBOL_GPL(vmbus_next_request_id);
>
> -/*
> - * vmbus_request_addr - Returns the memory address stored at @trans_id
> - * in @rqstor. Uses a spin lock to avoid race conditions.
> - * @channel: Pointer to the VMbus channel struct
> - * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
> - * next request id.
> - */
> -u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
> +/* As in vmbus_request_addr_match() but without the requestor lock */
> +u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
> + u64 rqst_addr)
> {
> struct vmbus_requestor *rqstor = &channel->requestor;
> - unsigned long flags;
> u64 req_addr;
>
> /* Check rqstor has been initialized */
> @@ -1300,25 +1294,60 @@ u64 vmbus_request_addr(struct vmbus_channel
> *channel, u64 trans_id)
> if (!trans_id)
> return VMBUS_RQST_ERROR;
>
> - spin_lock_irqsave(&rqstor->req_lock, flags);
> -
> /* Data corresponding to trans_id is stored at trans_id - 1 */
> trans_id--;
>
> /* Invalid trans_id */
> - if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {
> - spin_unlock_irqrestore(&rqstor->req_lock, flags);
> + if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap))
> return VMBUS_RQST_ERROR;
> - }
>
> req_addr = rqstor->req_arr[trans_id];
> - rqstor->req_arr[trans_id] = rqstor->next_request_id;
> - rqstor->next_request_id = trans_id;
> + if (rqst_addr == VMBUS_RQST_ADDR_ANY || req_addr == rqst_addr) {
> + rqstor->req_arr[trans_id] = rqstor->next_request_id;
> + rqstor->next_request_id = trans_id;
>
> - /* The already held spin lock provides atomicity */
> - bitmap_clear(rqstor->req_bitmap, trans_id, 1);
> + /* The already held spin lock provides atomicity */
> + bitmap_clear(rqstor->req_bitmap, trans_id, 1);
> + }
> +
> + return req_addr;
> +}
> +EXPORT_SYMBOL_GPL(__vmbus_request_addr_match);
> +
> +/*
> + * vmbus_request_addr_match - Clears/removes @trans_id from the @channel's
> + * requestor, provided the memory address stored at @trans_id equals @rqst_addr
> + * (or provided @rqst_addr matches the sentinel value VMBUS_RQST_ADDR_ANY).
> + *
> + * Returns the memory address stored at @trans_id, or VMBUS_RQST_ERROR if
> + * @trans_id is not contained in the requestor.
> + *
> + * Acquires and releases the requestor spin lock.
> + */
> +u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
> + u64 rqst_addr)
> +{
> + struct vmbus_requestor *rqstor = &channel->requestor;
> + unsigned long flags;
> + u64 req_addr;
>
> + spin_lock_irqsave(&rqstor->req_lock, flags);
> + req_addr = __vmbus_request_addr_match(channel, trans_id, rqst_addr);
> spin_unlock_irqrestore(&rqstor->req_lock, flags);
> +
> return req_addr;
> }
> +EXPORT_SYMBOL_GPL(vmbus_request_addr_match);
> +
> +/*
> + * vmbus_request_addr - Returns the memory address stored at @trans_id
> + * in @rqstor. Uses a spin lock to avoid race conditions.
> + * @channel: Pointer to the VMbus channel struct
> + * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
> + * next request id.
> + */
> +u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
> +{
> + return vmbus_request_addr_match(channel, trans_id,
> VMBUS_RQST_ADDR_ANY);
> +}
> EXPORT_SYMBOL_GPL(vmbus_request_addr);
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index a7cb596d893b1..c77d78f34b96a 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -788,6 +788,7 @@ struct vmbus_requestor {
>
> #define VMBUS_NO_RQSTOR U64_MAX
> #define VMBUS_RQST_ERROR (U64_MAX - 1)
> +#define VMBUS_RQST_ADDR_ANY U64_MAX
> /* NetVSC-specific */
> #define VMBUS_RQST_ID_NO_RESPONSE (U64_MAX - 2)
> /* StorVSC-specific */
> @@ -1042,6 +1043,10 @@ struct vmbus_channel {
> };
>
> u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr);
> +u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
> + u64 rqst_addr);
> +u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
> + u64 rqst_addr);
> u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id);
>
> static inline bool is_hvsock_channel(const struct vmbus_channel *c)
> --
> 2.25.1
Reviewed-by: Michael Kelley <[email protected]>