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Subject[PATCH v2 3/7] vmw_balloon: VMCI_DOORBELL_SET does not check status
Date
When vmballoon_vmci_init() sets a doorbell using VMCI_DOORBELL_SET, for
some reason it does not consider the status and looks at the result.
However, the hypervisor does not update the result - it updates the
status. This might cause VMCI doorbell not to be enabled, resulting in
degraded performance.

Fixes: 48e3d668b790 ("VMware balloon: Enable notification via VMCI")

Cc: stable@vger.kernel.org
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
drivers/misc/vmw_balloon.c | 37 +++++++++++++++++++------------------
1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 60ab83d3d0ef..a7df4c24a28d 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -1036,29 +1036,30 @@ static void vmballoon_vmci_cleanup(struct vmballoon *b)
*/
static int vmballoon_vmci_init(struct vmballoon *b)
{
- int error = 0;
+ unsigned long error, dummy;

- if ((b->capabilities & VMW_BALLOON_SIGNALLED_WAKEUP_CMD) != 0) {
- error = vmci_doorbell_create(&b->vmci_doorbell,
- VMCI_FLAG_DELAYED_CB,
- VMCI_PRIVILEGE_FLAG_RESTRICTED,
- vmballoon_doorbell, b);
-
- if (error == VMCI_SUCCESS) {
- VMWARE_BALLOON_CMD(VMCI_DOORBELL_SET,
- b->vmci_doorbell.context,
- b->vmci_doorbell.resource, error);
- STATS_INC(b->stats.doorbell_set);
- }
- }
+ if ((b->capabilities & VMW_BALLOON_SIGNALLED_WAKEUP_CMD) == 0)
+ return 0;

- if (error != 0) {
- vmballoon_vmci_cleanup(b);
+ error = vmci_doorbell_create(&b->vmci_doorbell, VMCI_FLAG_DELAYED_CB,
+ VMCI_PRIVILEGE_FLAG_RESTRICTED,
+ vmballoon_doorbell, b);

- return -EIO;
- }
+ if (error != VMCI_SUCCESS)
+ goto fail;
+
+ error = VMWARE_BALLOON_CMD(VMCI_DOORBELL_SET, b->vmci_doorbell.context,
+ b->vmci_doorbell.resource, dummy);
+
+ STATS_INC(b->stats.doorbell_set);
+
+ if (error != VMW_BALLOON_SUCCESS)
+ goto fail;

return 0;
+fail:
+ vmballoon_vmci_cleanup(b);
+ return -EIO;
}

/*
--
2.17.0
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