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authorJeff Kirsher <jeffrey.t.kirsher@intel.com>2015-04-03 23:27:07 +0300
committerJeff Kirsher <jeffrey.t.kirsher@intel.com>2015-04-15 01:48:17 +0300
commitada2411d4fce4c55cfe04cdd9ed3dc2c5fe6523a (patch)
tree52d3c3998fd9f3d8722ef8d5fa9e7cb5b42bcf30 /drivers
parent9de15bda37bd9b86378afd82e6fc52e82dc89ac3 (diff)
downloadlinux-ada2411d4fce4c55cfe04cdd9ed3dc2c5fe6523a.tar.xz
fm10k: comment next_vf_mbx flow
Add a header comment explaining why we have the somewhat crazy mailbox flow. This flow is necessary as it prevents the PF<->SM mailbox from being flooded by the VF messages, which normally trigger a message to the PF. This helps prevent the case where we see a PF mailbox timeout. Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Acked-by: Matthew Vick <matthew.vick@intel.com> Tested-by: Krishneil Singh <krishneil.k.singh@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/ethernet/intel/fm10k/fm10k_iov.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_iov.c b/drivers/net/ethernet/intel/fm10k/fm10k_iov.c
index 0b37e197e300..5b08e6284a3c 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k_iov.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_iov.c
@@ -113,6 +113,13 @@ s32 fm10k_iov_mbx(struct fm10k_intfc *interface)
/* lock the mailbox for transmit and receive */
fm10k_mbx_lock(interface);
+ /* Most VF messages sent to the PF cause the PF to respond by
+ * requesting from the SM mailbox. This means that too many VF
+ * messages processed at once could cause a mailbox timeout on the PF.
+ * To prevent this, store a pointer to the next VF mbx to process. Use
+ * that as the start of the loop so that we don't starve whichever VF
+ * got ignored on the previous run.
+ */
process_mbx:
for (i = iov_data->next_vf_mbx ? : iov_data->num_vfs; i--;) {
struct fm10k_vf_info *vf_info = &iov_data->vf_info[i];
@@ -137,6 +144,10 @@ process_mbx:
mbx->ops.process(hw, mbx);
}
+ /* if we stopped processing mailboxes early, update next_vf_mbx.
+ * Otherwise, reset next_vf_mbx, and restart loop so that we process
+ * the remaining mailboxes we skipped at the start.
+ */
if (i >= 0) {
iov_data->next_vf_mbx = i + 1;
} else if (iov_data->next_vf_mbx) {