From 0aadb6a7bb811554cf39318b5d18e8ec50dd9f02 Mon Sep 17 00:00:00 2001 From: Andrea Parri (Microsoft) Date: Tue, 19 Apr 2022 14:23:23 +0200 Subject: Drivers: hv: vmbus: Introduce vmbus_request_addr_match() 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 Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20220419122325.10078-5-parri.andrea@gmail.com Signed-off-by: Wei Liu --- drivers/hv/channel.c | 65 +++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 47 insertions(+), 18 deletions(-) (limited to 'drivers/hv') diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index 585a8084848b..49f10a603a09 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); -- cgit v1.2.3