[PATCH 1/1] Staging: hv: util: Invoke cn_netlink_send() in a work context

From: K. Y. Srinivasan
Date: Sun Oct 09 2011 - 22:19:40 EST


Invoke cn_netlink_send() in a work context as opposed being called
in the context of channel callback. On entry into the channel callback
code the channel inbound spin lock is held and deferring to a work
context avoids having to invoke cn_netlink_send() while holding
the inbound lock. As part of this adjustment, also increase the
timeout value for waiting for the user level component of KVP.

Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
---
drivers/staging/hv/hv_kvp.c | 18 +++++++++++-------
1 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/hv/hv_kvp.c b/drivers/staging/hv/hv_kvp.c
index 307aedc..1e9515c 100644
--- a/drivers/staging/hv/hv_kvp.c
+++ b/drivers/staging/hv/hv_kvp.c
@@ -44,11 +44,12 @@
static struct {
bool active; /* transaction status - active or not */
int recv_len; /* number of bytes received. */
+ int index; /* current index */
struct vmbus_channel *recv_channel; /* chn we got the request */
u64 recv_req_id; /* request ID. */
} kvp_transaction;

-static int kvp_send_key(int index);
+static void kvp_send_key(struct work_struct *dummy);

#define TIMEOUT_FIRED 1

@@ -57,6 +58,7 @@ static void kvp_work_func(struct work_struct *dummy);
static void kvp_register(void);

static DECLARE_DELAYED_WORK(kvp_work, kvp_work_func);
+static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);

static struct cb_id kvp_id = { CN_KVP_IDX, CN_KVP_VAL };
static const char kvp_name[] = "kvp_kernel_module";
@@ -121,10 +123,11 @@ kvp_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
}
}

-static int
-kvp_send_key(int index)
+static void
+kvp_send_key(struct work_struct *dummy)
{
struct cn_msg *msg;
+ int index = kvp_transaction.index;

msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);

@@ -136,9 +139,8 @@ kvp_send_key(int index)
msg->len = sizeof(struct hv_ku_msg);
cn_netlink_send(msg, 0, GFP_ATOMIC);
kfree(msg);
- return 0;
}
- return 1;
+ return;
}

/*
@@ -286,6 +288,7 @@ void hv_kvp_onchannelcallback(void *context)
kvp_transaction.recv_channel = channel;
kvp_transaction.recv_req_id = requestid;
kvp_transaction.active = true;
+ kvp_transaction.index = kvp_data->index;

/*
* Get the information from the
@@ -296,8 +299,8 @@ void hv_kvp_onchannelcallback(void *context)
* Set a timeout to deal with
* user-mode not responding.
*/
- kvp_send_key(kvp_data->index);
- schedule_delayed_work(&kvp_work, 100);
+ schedule_work(&kvp_sendkey_work);
+ schedule_delayed_work(&kvp_work, 5*HZ);

return;

@@ -332,4 +335,5 @@ void hv_kvp_deinit(void)
{
cn_del_callback(&kvp_id);
cancel_delayed_work_sync(&kvp_work);
+ cancel_work_sync(&kvp_sendkey_work);
}
--
1.7.4.1

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