This is a note to let you know that I've just added the patch titled
Drivers: hv: vmbus: Cleanup hv_post_message()
to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From b29ef3546aecb253a5552b198cef23750d56e1e4 Mon Sep 17 00:00:00 2001
From: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Date: Thu, 28 Aug 2014 18:29:52 -0700
Subject: Drivers: hv: vmbus: Cleanup hv_post_message()
Minimize failures in this function by pre-allocating the buffer
for posting messages. The hypercall for posting the message can fail
for a number of reasons:
1. Transient resource related issues
2. Buffer alignment
3. Buffer cannot span a page boundry
We address issues 2 and 3 by preallocating a per-cpu page for the buffer.
Transient resource related failures are handled by retrying by the callers
of this function.
This patch is based on the investigation
done by Dexuan Cui <decui@xxxxxxxxxxxxx>.
I would like to thank Sitsofe Wheeler <sitsofe@xxxxxxxxx>
for reporting the issue and helping in debuggging.
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Reported-by: Sitsofe Wheeler <sitsofe@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Tested-by: Sitsofe Wheeler <sitsofe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/hv/hv.c | 27 +++++++++++++++------------
drivers/hv/hyperv_vmbus.h | 4 ++++
2 files changed, 19 insertions(+), 12 deletions(-)
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index edfc8488cb03..3e4235c7a47f 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -138,6 +138,8 @@ int hv_init(void)
memset(hv_context.synic_event_page, 0, sizeof(void *) * NR_CPUS);
memset(hv_context.synic_message_page, 0,
sizeof(void *) * NR_CPUS);
+ memset(hv_context.post_msg_page, 0,
+ sizeof(void *) * NR_CPUS);
memset(hv_context.vp_index, 0,
sizeof(int) * NR_CPUS);
memset(hv_context.event_dpc, 0,
@@ -217,26 +219,18 @@ int hv_post_message(union hv_connection_id connection_id,
enum hv_message_type message_type,
void *payload, size_t payload_size)
{
- struct aligned_input {
- u64 alignment8;
- struct hv_input_post_message msg;
- };
struct hv_input_post_message *aligned_msg;
u16 status;
- unsigned long addr;
if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
return -EMSGSIZE;
- addr = (unsigned long)kmalloc(sizeof(struct aligned_input), GFP_ATOMIC);
- if (!addr)
- return -ENOMEM;
-
aligned_msg = (struct hv_input_post_message *)
- (ALIGN(addr, HV_HYPERCALL_PARAM_ALIGN));
+ hv_context.post_msg_page[get_cpu()];
aligned_msg->connectionid = connection_id;
+ aligned_msg->reserved = 0;
aligned_msg->message_type = message_type;
aligned_msg->payload_size = payload_size;
memcpy((void *)aligned_msg->payload, payload, payload_size);
@@ -244,8 +238,7 @@ int hv_post_message(union hv_connection_id connection_id,
status = do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL)
& 0xFFFF;
- kfree((void *)addr);
-
+ put_cpu();
return status;
}
@@ -294,6 +287,14 @@ int hv_synic_alloc(void)
pr_err("Unable to allocate SYNIC event page\n");
goto err;
}
+
+ hv_context.post_msg_page[cpu] =
+ (void *)get_zeroed_page(GFP_ATOMIC);
+
+ if (hv_context.post_msg_page[cpu] == NULL) {
+ pr_err("Unable to allocate post msg page\n");
+ goto err;
+ }
}
return 0;
@@ -308,6 +309,8 @@ static void hv_synic_free_cpu(int cpu)
free_page((unsigned long)hv_context.synic_event_page[cpu]);
if (hv_context.synic_message_page[cpu])
free_page((unsigned long)hv_context.synic_message_page[cpu]);
+ if (hv_context.post_msg_page[cpu])
+ free_page((unsigned long)hv_context.post_msg_page[cpu]);
}
void hv_synic_free(void)
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 22b750749a39..c386d8dc7223 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -515,6 +515,10 @@ struct hv_context {
* per-cpu list of the channels based on their CPU affinity.
*/
struct list_head percpu_list[NR_CPUS];
+ /*
+ * buffer to post messages to the host.
+ */
+ void *post_msg_page[NR_CPUS];
};
extern struct hv_context hv_context;
--
2.1.0
--
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