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authorOlaf Hering <olaf@aepfle.de>2015-12-14 16:01:33 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-09-15 08:27:40 +0200
commitb125fabf22d44f7c57e6df2a21d27add8385df0d (patch)
tree49268b93b6bde34ea8155ddec3d4a59cbfe4d3a7
parente31409cd1ae44450964fc29e2bb0519cc50f5923 (diff)
downloadlinux-linaro-stable-b125fabf22d44f7c57e6df2a21d27add8385df0d.tar.gz
Drivers: hv: utils: run polling callback always in interrupt context
[ Upstream commit 3cace4a616108539e2730f8dc21a636474395e0f ] All channel interrupts are bound to specific VCPUs in the guest at the point channel is created. While currently, we invoke the polling function on the correct CPU (the CPU to which the channel is bound to) in some cases we may run the polling function in a non-interrupt context. This potentially can cause an issue as the polling function can be interrupted by the channel callback function. Fix the issue by running the polling function on the appropriate CPU at interrupt level. Additional details of the issue being addressed by this patch are given below: Currently hv_fcopy_onchannelcallback is called from interrupts and also via the ->write function of hv_utils. Since the used global variables to maintain state are not thread safe the state can get out of sync. This affects the variable state as well as the channel inbound buffer. As suggested by KY adjust hv_poll_channel to always run the given callback on the cpu which the channel is bound to. This avoids the need for locking because all the util services are single threaded and only one transaction is active at any given point in time. Additionally, remove the context variable, they will always be the same as recv_channel. Signed-off-by: Olaf Hering <olaf@aepfle.de> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/hv/hv_fcopy.c34
-rw-r--r--drivers/hv/hv_kvp.c28
-rw-r--r--drivers/hv/hv_snapshot.c29
-rw-r--r--drivers/hv/hyperv_vmbus.h6
4 files changed, 34 insertions, 63 deletions
diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index bbdec50c4a1c..c37a71e13de0 100644
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -51,7 +51,6 @@ static struct {
struct hv_fcopy_hdr *fcopy_msg; /* current message */
struct vmbus_channel *recv_channel; /* chn we got the request */
u64 recv_req_id; /* request ID. */
- void *fcopy_context; /* for the channel callback */
} fcopy_transaction;
static void fcopy_respond_to_host(int error);
@@ -67,6 +66,13 @@ static struct hvutil_transport *hvt;
*/
static int dm_reg_value;
+static void fcopy_poll_wrapper(void *channel)
+{
+ /* Transaction is finished, reset the state here to avoid races. */
+ fcopy_transaction.state = HVUTIL_READY;
+ hv_fcopy_onchannelcallback(channel);
+}
+
static void fcopy_timeout_func(struct work_struct *dummy)
{
/*
@@ -74,13 +80,7 @@ static void fcopy_timeout_func(struct work_struct *dummy)
* process the pending transaction.
*/
fcopy_respond_to_host(HV_E_FAIL);
-
- /* Transaction is finished, reset the state. */
- if (fcopy_transaction.state > HVUTIL_READY)
- fcopy_transaction.state = HVUTIL_READY;
-
- hv_poll_channel(fcopy_transaction.fcopy_context,
- hv_fcopy_onchannelcallback);
+ hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
}
static int fcopy_handle_handshake(u32 version)
@@ -108,9 +108,7 @@ static int fcopy_handle_handshake(u32 version)
return -EINVAL;
}
pr_debug("FCP: userspace daemon ver. %d registered\n", version);
- fcopy_transaction.state = HVUTIL_READY;
- hv_poll_channel(fcopy_transaction.fcopy_context,
- hv_fcopy_onchannelcallback);
+ hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
return 0;
}
@@ -227,15 +225,8 @@ void hv_fcopy_onchannelcallback(void *context)
int util_fw_version;
int fcopy_srv_version;
- if (fcopy_transaction.state > HVUTIL_READY) {
- /*
- * We will defer processing this callback once
- * the current transaction is complete.
- */
- fcopy_transaction.fcopy_context = context;
+ if (fcopy_transaction.state > HVUTIL_READY)
return;
- }
- fcopy_transaction.fcopy_context = NULL;
vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
&requestid);
@@ -305,9 +296,8 @@ static int fcopy_on_msg(void *msg, int len)
if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
fcopy_transaction.state = HVUTIL_USERSPACE_RECV;
fcopy_respond_to_host(*val);
- fcopy_transaction.state = HVUTIL_READY;
- hv_poll_channel(fcopy_transaction.fcopy_context,
- hv_fcopy_onchannelcallback);
+ hv_poll_channel(fcopy_transaction.recv_channel,
+ fcopy_poll_wrapper);
}
return 0;
diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index e6aa33a89b0e..2a3420c4ca59 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -66,7 +66,6 @@ static struct {
struct hv_kvp_msg *kvp_msg; /* current message */
struct vmbus_channel *recv_channel; /* chn we got the request */
u64 recv_req_id; /* request ID. */
- void *kvp_context; /* for the channel callback */
} kvp_transaction;
/*
@@ -94,6 +93,13 @@ static struct hvutil_transport *hvt;
*/
#define HV_DRV_VERSION "3.1"
+static void kvp_poll_wrapper(void *channel)
+{
+ /* Transaction is finished, reset the state here to avoid races. */
+ kvp_transaction.state = HVUTIL_READY;
+ hv_kvp_onchannelcallback(channel);
+}
+
static void
kvp_register(int reg_value)
{
@@ -121,12 +127,7 @@ static void kvp_timeout_func(struct work_struct *dummy)
*/
kvp_respond_to_host(NULL, HV_E_FAIL);
- /* Transaction is finished, reset the state. */
- if (kvp_transaction.state > HVUTIL_READY)
- kvp_transaction.state = HVUTIL_READY;
-
- hv_poll_channel(kvp_transaction.kvp_context,
- hv_kvp_onchannelcallback);
+ hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
}
static int kvp_handle_handshake(struct hv_kvp_msg *msg)
@@ -218,9 +219,7 @@ static int kvp_on_msg(void *msg, int len)
*/
if (cancel_delayed_work_sync(&kvp_timeout_work)) {
kvp_respond_to_host(message, error);
- kvp_transaction.state = HVUTIL_READY;
- hv_poll_channel(kvp_transaction.kvp_context,
- hv_kvp_onchannelcallback);
+ hv_poll_channel(kvp_transaction.recv_channel, kvp_poll_wrapper);
}
return 0;
@@ -596,15 +595,8 @@ void hv_kvp_onchannelcallback(void *context)
int util_fw_version;
int kvp_srv_version;
- if (kvp_transaction.state > HVUTIL_READY) {
- /*
- * We will defer processing this callback once
- * the current transaction is complete.
- */
- kvp_transaction.kvp_context = context;
+ if (kvp_transaction.state > HVUTIL_READY)
return;
- }
- kvp_transaction.kvp_context = NULL;
vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 4, &recvlen,
&requestid);
diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index 815405f2e777..a548ae42c927 100644
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -53,7 +53,6 @@ static struct {
struct vmbus_channel *recv_channel; /* chn we got the request */
u64 recv_req_id; /* request ID. */
struct hv_vss_msg *msg; /* current message */
- void *vss_context; /* for the channel callback */
} vss_transaction;
@@ -74,6 +73,13 @@ static void vss_timeout_func(struct work_struct *dummy);
static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
static DECLARE_WORK(vss_send_op_work, vss_send_op);
+static void vss_poll_wrapper(void *channel)
+{
+ /* Transaction is finished, reset the state here to avoid races. */
+ vss_transaction.state = HVUTIL_READY;
+ hv_vss_onchannelcallback(channel);
+}
+
/*
* Callback when data is received from user mode.
*/
@@ -86,12 +92,7 @@ static void vss_timeout_func(struct work_struct *dummy)
pr_warn("VSS: timeout waiting for daemon to reply\n");
vss_respond_to_host(HV_E_FAIL);
- /* Transaction is finished, reset the state. */
- if (vss_transaction.state > HVUTIL_READY)
- vss_transaction.state = HVUTIL_READY;
-
- hv_poll_channel(vss_transaction.vss_context,
- hv_vss_onchannelcallback);
+ hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
}
static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
@@ -138,9 +139,8 @@ static int vss_on_msg(void *msg, int len)
if (cancel_delayed_work_sync(&vss_timeout_work)) {
vss_respond_to_host(vss_msg->error);
/* Transaction is finished, reset the state. */
- vss_transaction.state = HVUTIL_READY;
- hv_poll_channel(vss_transaction.vss_context,
- hv_vss_onchannelcallback);
+ hv_poll_channel(vss_transaction.recv_channel,
+ vss_poll_wrapper);
}
} else {
/* This is a spurious call! */
@@ -238,15 +238,8 @@ void hv_vss_onchannelcallback(void *context)
struct icmsg_hdr *icmsghdrp;
struct icmsg_negotiate *negop = NULL;
- if (vss_transaction.state > HVUTIL_READY) {
- /*
- * We will defer processing this callback once
- * the current transaction is complete.
- */
- vss_transaction.vss_context = context;
+ if (vss_transaction.state > HVUTIL_READY)
return;
- }
- vss_transaction.vss_context = NULL;
vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
&requestid);
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 225b96bcf7fe..12156db2e88e 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -764,11 +764,7 @@ static inline void hv_poll_channel(struct vmbus_channel *channel,
if (!channel)
return;
- if (channel->target_cpu != smp_processor_id())
- smp_call_function_single(channel->target_cpu,
- cb, channel, true);
- else
- cb(channel);
+ smp_call_function_single(channel->target_cpu, cb, channel, true);
}
enum hvutil_device_state {