Re: [PATCH 2/3]: Staging: hv: Use native wait primitives
On Tue, Feb 15, 2011 at 05:52:46PM +, KY Srinivasan wrote: If I understand you correctly, you would be prefer to have unbounded waiting with comments justifying why we cannot have timeouts. I will roll out a patch once the tree stabilizes. Just make sure to add a comment explaining why the wait is unbounded. -- Dmitry ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
RE: [PATCH 2/3]: Staging: hv: Use native wait primitives
-Original Message- From: Jiri Slaby [mailto:jirisl...@gmail.com] Sent: Tuesday, February 15, 2011 4:21 AM To: KY Srinivasan Cc: gre...@suse.de; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On 02/11/2011 06:59 PM, K. Y. Srinivasan wrote: In preperation for getting rid of the osd layer; change the code to use native wait interfaces. As part of this, fixed the buggy implementation in the osd_wait_primitive where the condition was cleared potentially after the condition was signalled. ... @@ -566,7 +567,11 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer, } } - osd_waitevent_wait(msginfo-waitevent); + wait_event_timeout(msginfo-waitevent, + msginfo-wait_condition, + msecs_to_jiffies(1000)); + BUG_ON(msginfo-wait_condition == 0); The added BUG_ONs all over the code look scary. These shouldn't be BUG_ONs at all. You should maybe warn and bail out, but not kill the whole machine. This is Linux code running as a guest on a Windows host; and so the guest cannot tolerate a failure of the host. In the cases where I have chosen to BUG_ON, there is no reasonable recovery possible when the host is non-functional (as determined by a non-responsive host). And looking at the code, more appropriate would be completion instead of wait events. And msecs_to_jiffies(1000) == HZ. Agreed. In this first round of cleanup, I chose to keep the primitives as they were in osd.c. Greg, if it is ok with you, I will send you a patch that fixes these issues on top of the patches I have already sent. Regards, K. Y @@ -689,7 +693,8 @@ static void vmbus_ongpadl_torndown( memcpy(msginfo-response.gpadl_torndown, gpadl_torndown, sizeof(struct vmbus_channel_gpadl_torndown)); - osd_waitevent_set(msginfo-waitevent); + msginfo-wait_condition = 1; + wake_up(msginfo-waitevent); break; } } @@ -730,7 +735,8 @@ static void vmbus_onversion_response( memcpy(msginfo-response.version_response, version_response, sizeof(struct vmbus_channel_version_response)); - osd_waitevent_set(msginfo-waitevent); + msginfo-wait_condition = 1; + wake_up(msginfo-waitevent); } } spin_unlock_irqrestore(vmbus_connection.channelmsg_lock, flags); regards, -- js ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
Re: [PATCH 2/3]: Staging: hv: Use native wait primitives
On Tue, Feb 15, 2011 at 01:35:56PM +, KY Srinivasan wrote: -Original Message- From: Jiri Slaby [mailto:jirisl...@gmail.com] Sent: Tuesday, February 15, 2011 4:21 AM To: KY Srinivasan Cc: gre...@suse.de; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On 02/11/2011 06:59 PM, K. Y. Srinivasan wrote: In preperation for getting rid of the osd layer; change the code to use native wait interfaces. As part of this, fixed the buggy implementation in the osd_wait_primitive where the condition was cleared potentially after the condition was signalled. ... @@ -566,7 +567,11 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer, } } - osd_waitevent_wait(msginfo-waitevent); + wait_event_timeout(msginfo-waitevent, + msginfo-wait_condition, + msecs_to_jiffies(1000)); + BUG_ON(msginfo-wait_condition == 0); The added BUG_ONs all over the code look scary. These shouldn't be BUG_ONs at all. You should maybe warn and bail out, but not kill the whole machine. This is Linux code running as a guest on a Windows host; and so the guest cannot tolerate a failure of the host. In the cases where I have chosen to BUG_ON, there is no reasonable recovery possible when the host is non-functional (as determined by a non-responsive host). If you have a non-responsive host, wouldn't that imply that this guest code wouldn't run at all? :) Having BUG_ON() in drivers is not a good idea either way. Please remove these in future patches. And looking at the code, more appropriate would be completion instead of wait events. And msecs_to_jiffies(1000) == HZ. Agreed. In this first round of cleanup, I chose to keep the primitives as they were in osd.c. Greg, if it is ok with you, I will send you a patch that fixes these issues on top of the patches I have already sent. Yes, that is fine. thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
RE: [PATCH 2/3]: Staging: hv: Use native wait primitives
-Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Tuesday, February 15, 2011 9:03 AM To: KY Srinivasan Cc: Jiri Slaby; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On Tue, Feb 15, 2011 at 01:35:56PM +, KY Srinivasan wrote: -Original Message- From: Jiri Slaby [mailto:jirisl...@gmail.com] Sent: Tuesday, February 15, 2011 4:21 AM To: KY Srinivasan Cc: gre...@suse.de; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On 02/11/2011 06:59 PM, K. Y. Srinivasan wrote: In preperation for getting rid of the osd layer; change the code to use native wait interfaces. As part of this, fixed the buggy implementation in the osd_wait_primitive where the condition was cleared potentially after the condition was signalled. ... @@ -566,7 +567,11 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer, } } - osd_waitevent_wait(msginfo-waitevent); + wait_event_timeout(msginfo-waitevent, + msginfo-wait_condition, + msecs_to_jiffies(1000)); + BUG_ON(msginfo-wait_condition == 0); The added BUG_ONs all over the code look scary. These shouldn't be BUG_ONs at all. You should maybe warn and bail out, but not kill the whole machine. This is Linux code running as a guest on a Windows host; and so the guest cannot tolerate a failure of the host. In the cases where I have chosen to BUG_ON, there is no reasonable recovery possible when the host is non-functional (as determined by a non-responsive host). If you have a non-responsive host, wouldn't that imply that this guest code wouldn't run at all? :) The fact that on a particular transaction the host has not responded within an expected time interval does not necessarily mean that the guest code would not be running. There may be issues on the host side that may be either transient or permanent that may cause problems like this. Keep in mind, HyperV is a type 1 hypervisor that would schedule all VMs including the host and so, guest would get scheduled. Having BUG_ON() in drivers is not a good idea either way. Please remove these in future patches. In situations where there is not a reasonable rollback strategy (for instance in one of the cases, we are granting access to the guest physical pages to the host) we really have only 2 options: 1) Wait until the host responds. This wait could potentially be unbounded and in fact this was the way the code was to begin with. One of the reviewers had suggested that unbounded wait was to be corrected. 2) Wait for a specific period and if the host does not respond within a reasonable period, kill the guest since there is no recovery possible. I chose option 2, as part of addressing some of the prior review comments. If the consensus now is to go back to option 1, I am fine with that; I will send you a patch to rectify this. Regards, K. Y And looking at the code, more appropriate would be completion instead of wait events. And msecs_to_jiffies(1000) == HZ. Agreed. In this first round of cleanup, I chose to keep the primitives as they were in osd.c. Greg, if it is ok with you, I will send you a patch that fixes these issues on top of the patches I have already sent. Yes, that is fine. thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
Re: [PATCH 2/3]: Staging: hv: Use native wait primitives
On Tue, Feb 15, 2011 at 04:22:20PM +, KY Srinivasan wrote: -Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Tuesday, February 15, 2011 9:03 AM To: KY Srinivasan Cc: Jiri Slaby; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On Tue, Feb 15, 2011 at 01:35:56PM +, KY Srinivasan wrote: -Original Message- From: Jiri Slaby [mailto:jirisl...@gmail.com] Sent: Tuesday, February 15, 2011 4:21 AM To: KY Srinivasan Cc: gre...@suse.de; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On 02/11/2011 06:59 PM, K. Y. Srinivasan wrote: In preperation for getting rid of the osd layer; change the code to use native wait interfaces. As part of this, fixed the buggy implementation in the osd_wait_primitive where the condition was cleared potentially after the condition was signalled. ... @@ -566,7 +567,11 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer, } } - osd_waitevent_wait(msginfo-waitevent); + wait_event_timeout(msginfo-waitevent, + msginfo-wait_condition, + msecs_to_jiffies(1000)); + BUG_ON(msginfo-wait_condition == 0); The added BUG_ONs all over the code look scary. These shouldn't be BUG_ONs at all. You should maybe warn and bail out, but not kill the whole machine. This is Linux code running as a guest on a Windows host; and so the guest cannot tolerate a failure of the host. In the cases where I have chosen to BUG_ON, there is no reasonable recovery possible when the host is non-functional (as determined by a non-responsive host). If you have a non-responsive host, wouldn't that imply that this guest code wouldn't run at all? :) The fact that on a particular transaction the host has not responded within an expected time interval does not necessarily mean that the guest code would not be running. There may be issues on the host side that may be either transient or permanent that may cause problems like this. Keep in mind, HyperV is a type 1 hypervisor that would schedule all VMs including the host and so, guest would get scheduled. Having BUG_ON() in drivers is not a good idea either way. Please remove these in future patches. In situations where there is not a reasonable rollback strategy (for instance in one of the cases, we are granting access to the guest physical pages to the host) we really have only 2 options: 1) Wait until the host responds. This wait could potentially be unbounded and in fact this was the way the code was to begin with. One of the reviewers had suggested that unbounded wait was to be corrected. 2) Wait for a specific period and if the host does not respond within a reasonable period, kill the guest since there is no recovery possible. Killing the guest is a very serious thing, causing all sorts of possible problems with it, right? I chose option 2, as part of addressing some of the prior review comments. If the consensus now is to go back to option 1, I am fine with that; Unbounded waits aren't ok either, you need some sort of timeout. But, as this is a bit preferable to dieing, I suggest doing this, and comment the heck out of it to explain all of this for anyone who reads it. thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
RE: [PATCH 2/3]: Staging: hv: Use native wait primitives
-Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Tuesday, February 15, 2011 11:30 AM To: KY Srinivasan Cc: Jiri Slaby; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On Tue, Feb 15, 2011 at 04:22:20PM +, KY Srinivasan wrote: -Original Message- From: Greg KH [mailto:gre...@suse.de] Sent: Tuesday, February 15, 2011 9:03 AM To: KY Srinivasan Cc: Jiri Slaby; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On Tue, Feb 15, 2011 at 01:35:56PM +, KY Srinivasan wrote: -Original Message- From: Jiri Slaby [mailto:jirisl...@gmail.com] Sent: Tuesday, February 15, 2011 4:21 AM To: KY Srinivasan Cc: gre...@suse.de; linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; virtualizat...@lists.osdl.org Subject: Re: [PATCH 2/3]: Staging: hv: Use native wait primitives On 02/11/2011 06:59 PM, K. Y. Srinivasan wrote: In preperation for getting rid of the osd layer; change the code to use native wait interfaces. As part of this, fixed the buggy implementation in the osd_wait_primitive where the condition was cleared potentially after the condition was signalled. ... @@ -566,7 +567,11 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer, } } - osd_waitevent_wait(msginfo-waitevent); + wait_event_timeout(msginfo-waitevent, + msginfo-wait_condition, + msecs_to_jiffies(1000)); + BUG_ON(msginfo-wait_condition == 0); The added BUG_ONs all over the code look scary. These shouldn't be BUG_ONs at all. You should maybe warn and bail out, but not kill the whole machine. This is Linux code running as a guest on a Windows host; and so the guest cannot tolerate a failure of the host. In the cases where I have chosen to BUG_ON, there is no reasonable recovery possible when the host is non-functional (as determined by a non-responsive host). If you have a non-responsive host, wouldn't that imply that this guest code wouldn't run at all? :) The fact that on a particular transaction the host has not responded within an expected time interval does not necessarily mean that the guest code would not be running. There may be issues on the host side that may be either transient or permanent that may cause problems like this. Keep in mind, HyperV is a type 1 hypervisor that would schedule all VMs including the host and so, guest would get scheduled. Having BUG_ON() in drivers is not a good idea either way. Please remove these in future patches. In situations where there is not a reasonable rollback strategy (for instance in one of the cases, we are granting access to the guest physical pages to the host) we really have only 2 options: 1) Wait until the host responds. This wait could potentially be unbounded and in fact this was the way the code was to begin with. One of the reviewers had suggested that unbounded wait was to be corrected. 2) Wait for a specific period and if the host does not respond within a reasonable period, kill the guest since there is no recovery possible. Killing the guest is a very serious thing, causing all sorts of possible problems with it, right? If there was a reasonable rollback strategy, I would not be killing the guest. I chose option 2, as part of addressing some of the prior review comments. If the consensus now is to go back to option 1, I am fine with that; Unbounded waits aren't ok either, you need some sort of timeout. But, as this is a bit preferable to dieing, I suggest doing this, and comment the heck out of it to explain all of this for anyone who reads it. If I understand you correctly, you would be prefer to have unbounded waiting with comments justifying why we cannot have timeouts. I will roll out a patch once the tree stabilizes. Regards, K. Y thanks, greg k-h ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
Re: [PATCH 2/3]: Staging: hv: Use native wait primitives
On 02/11/2011 06:59 PM, K. Y. Srinivasan wrote: In preperation for getting rid of the osd layer; change the code to use native wait interfaces. As part of this, fixed the buggy implementation in the osd_wait_primitive where the condition was cleared potentially after the condition was signalled. ... @@ -566,7 +567,11 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer, } } - osd_waitevent_wait(msginfo-waitevent); + wait_event_timeout(msginfo-waitevent, + msginfo-wait_condition, + msecs_to_jiffies(1000)); + BUG_ON(msginfo-wait_condition == 0); The added BUG_ONs all over the code look scary. These shouldn't be BUG_ONs at all. You should maybe warn and bail out, but not kill the whole machine. And looking at the code, more appropriate would be completion instead of wait events. And msecs_to_jiffies(1000) == HZ. @@ -689,7 +693,8 @@ static void vmbus_ongpadl_torndown( memcpy(msginfo-response.gpadl_torndown, gpadl_torndown, sizeof(struct vmbus_channel_gpadl_torndown)); - osd_waitevent_set(msginfo-waitevent); + msginfo-wait_condition = 1; + wake_up(msginfo-waitevent); break; } } @@ -730,7 +735,8 @@ static void vmbus_onversion_response( memcpy(msginfo-response.version_response, version_response, sizeof(struct vmbus_channel_version_response)); - osd_waitevent_set(msginfo-waitevent); + msginfo-wait_condition = 1; + wake_up(msginfo-waitevent); } } spin_unlock_irqrestore(vmbus_connection.channelmsg_lock, flags); regards, -- js ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
[PATCH 2/3]: Staging: hv: Use native wait primitives
In preperation for getting rid of the osd layer; change
the code to use native wait interfaces. As part of this,
fixed the buggy implementation in the osd_wait_primitive
where the condition was cleared potentially after the
condition was signalled.
Signed-off-by: K. Y. Srinivasan k...@microsoft.com
Signed-off-by: Hank Janssen hjans...@microsoft.com
---
drivers/staging/hv/channel.c | 58 +---
drivers/staging/hv/channel_mgmt.c | 46 +++-
drivers/staging/hv/channel_mgmt.h |4 +-
drivers/staging/hv/connection.c| 28 +++---
drivers/staging/hv/netvsc.c| 102 ++-
drivers/staging/hv/netvsc.h|3 +-
drivers/staging/hv/rndis_filter.c | 38 +
drivers/staging/hv/storvsc.c | 98 --
drivers/staging/hv/vmbus_private.h |3 +-
9 files changed, 208 insertions(+), 172 deletions(-)
diff --git a/drivers/staging/hv/channel.c b/drivers/staging/hv/channel.c
index 6c292e6..5a0923c 100644
--- a/drivers/staging/hv/channel.c
+++ b/drivers/staging/hv/channel.c
@@ -19,6 +19,8 @@
* Hank Janssen hjans...@microsoft.com
*/
#include linux/kernel.h
+#include linux/sched.h
+#include linux/wait.h
#include linux/mm.h
#include linux/slab.h
#include linux/module.h
@@ -243,11 +245,7 @@ int vmbus_open(struct vmbus_channel *newchannel, u32
send_ringbuffer_size,
goto errorout;
}
- openInfo-waitevent = osd_waitevent_create();
- if (!openInfo-waitevent) {
- err = -ENOMEM;
- goto errorout;
- }
+ init_waitqueue_head(openInfo-waitevent);
openMsg = (struct vmbus_channel_open_channel *)openInfo-msg;
openMsg-header.msgtype = CHANNELMSG_OPENCHANNEL;
@@ -280,8 +278,15 @@ int vmbus_open(struct vmbus_channel *newchannel, u32
send_ringbuffer_size,
goto Cleanup;
}
- /* FIXME: Need to time-out here */
- osd_waitevent_wait(openInfo-waitevent);
+ openInfo-wait_condition = 0;
+ wait_event_timeout(openInfo-waitevent,
+ openInfo-wait_condition,
+ msecs_to_jiffies(1000));
+ if (openInfo-wait_condition == 0) {
+ err = -ETIMEDOUT;
+ goto errorout;
+ }
+
if (openInfo-response.open_result.status == 0)
DPRINT_INFO(VMBUS, channel %p open success!!, newchannel);
@@ -294,7 +299,6 @@ Cleanup:
list_del(openInfo-msglistentry);
spin_unlock_irqrestore(vmbus_connection.channelmsg_lock, flags);
- kfree(openInfo-waitevent);
kfree(openInfo);
return 0;
@@ -509,11 +513,7 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel,
void *kbuffer,
if (ret)
return ret;
- msginfo-waitevent = osd_waitevent_create();
- if (!msginfo-waitevent) {
- ret = -ENOMEM;
- goto Cleanup;
- }
+ init_waitqueue_head(msginfo-waitevent);
gpadlmsg = (struct vmbus_channel_gpadl_header *)msginfo-msg;
gpadlmsg-header.msgtype = CHANNELMSG_GPADL_HEADER;
@@ -533,6 +533,7 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel,
void *kbuffer,
DPRINT_DBG(VMBUS, Sending GPADL Header - len %zd,
msginfo-msgsize - sizeof(*msginfo));
+ msginfo-wait_condition = 0;
ret = vmbus_post_msg(gpadlmsg, msginfo-msgsize -
sizeof(*msginfo));
if (ret != 0) {
@@ -566,7 +567,11 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel,
void *kbuffer,
}
}
- osd_waitevent_wait(msginfo-waitevent);
+ wait_event_timeout(msginfo-waitevent,
+ msginfo-wait_condition,
+ msecs_to_jiffies(1000));
+ BUG_ON(msginfo-wait_condition == 0);
+
/* At this point, we received the gpadl created msg */
DPRINT_DBG(VMBUS, Received GPADL created
@@ -582,7 +587,6 @@ Cleanup:
list_del(msginfo-msglistentry);
spin_unlock_irqrestore(vmbus_connection.channelmsg_lock, flags);
- kfree(msginfo-waitevent);
kfree(msginfo);
return ret;
}
@@ -605,11 +609,7 @@ int vmbus_teardown_gpadl(struct vmbus_channel *channel,
u32 gpadl_handle)
if (!info)
return -ENOMEM;
- info-waitevent = osd_waitevent_create();
- if (!info-waitevent) {
- kfree(info);
- return -ENOMEM;
- }
+ init_waitqueue_head(info-waitevent);
msg = (struct vmbus_channel_gpadl_teardown *)info-msg;
@@ -621,22 +621,20 @@ int vmbus_teardown_gpadl(struct vmbus_channel *channel,
u32 gpadl_handle)
list_add_tail(info-msglistentry,
vmbus_connection.chn_msg_list);
spin_unlock_irqrestore(vmbus_connection.channelmsg_lock, flags);
-
+ info-wait_condition = 0;
ret =
