From: Tim Sell <Timothy.Sell@xxxxxxxxxx>
The code that tests for high and low xmit watermarks was consolidated and
simplified. The output behavior should be identical, with the exception
of an off-by-one error being corrected in the tests done when the counters
overflowed.
Note that the literals passed to max() macros need to be explicitly
specified as unsigned long (UL), in order to prevent gcc warnings:
warning: comparison of distinct pointer types lacks a cast
Signed-off-by: Tim Sell <Timothy.Sell@xxxxxxxxxx>
Signed-off-by: Benjamin Romer <benjamin.romer@xxxxxxxxxx>
---
drivers/staging/unisys/visornic/visornic_main.c | 109 +++++++++++++++---------
1 file changed, 71 insertions(+), 38 deletions(-)
diff --git a/drivers/staging/unisys/visornic/visornic_main.c b/drivers/staging/unisys/visornic/visornic_main.c
index baa137e..bd58e15 100644
--- a/drivers/staging/unisys/visornic/visornic_main.c
+++ b/drivers/staging/unisys/visornic/visornic_main.c
@@ -134,15 +134,16 @@ struct visornic_devdata {
atomic_t num_rcvbuf_in_iovm;
unsigned long alloc_failed_in_if_needed_cnt;
unsigned long alloc_failed_in_repost_rtn_cnt;
- int max_outstanding_net_xmits; /* absolute max number of outstanding
- * xmits - should never hit this
- */
- int upper_threshold_net_xmits; /* high water mark for calling
- * netif_stop_queue()
- */
- int lower_threshold_net_xmits; /* high water mark for calling
- * netif_wake_queue()
- */
+ unsigned long max_outstanding_net_xmits; /* absolute max number of
+ * outstanding xmits - should
+ * never hit this
+ */
+ unsigned long upper_threshold_net_xmits; /* high water mark for
+ * calling netif_stop_queue()
+ */
+ unsigned long lower_threshold_net_xmits; /* high water mark for calling
+ * netif_wake_queue()
+ */
struct sk_buff_head xmitbufhead; /* xmitbufhead is the head of the
* xmit buffer list that have been
* sent to the IOPART end
@@ -779,6 +780,53 @@ visornic_close(struct net_device *netdev)
}
/**
+ * devdata_xmits_outstanding - compute outstanding xmits
+ * @devdata: visornic_devdata for device
+ *
+ * Return value is the number of outstanding xmits.
+ */
+static unsigned long devdata_xmits_outstanding(struct visornic_devdata *devdata)
+{
+ if (devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done)
+ return devdata->chstat.sent_xmit -
+ devdata->chstat.got_xmit_done;
+ else
+ return (ULONG_MAX - devdata->chstat.got_xmit_done
+ + devdata->chstat.sent_xmit + 1);
+}
+
+/**
+ * vnic_hit_high_watermark
+ * @devdata: indicates visornic device we are checking
+ * @high_watermark: max num of unacked xmits we will tolerate,
+ * before we will start throttling
+ *
+ * Returns true iff the number of unacked xmits sent to
+ * the IO partition is >= high_watermark.
+ */
+static inline bool vnic_hit_high_watermark(struct visornic_devdata *devdata,
+ ulong high_watermark)
+{
+ return (devdata_xmits_outstanding(devdata) >= high_watermark);
+}
+
+/**
+ * vnic_hit_low_watermark
+ * @devdata: indicates visornic device we are checking
+ * @low_watermark: we will wait until the num of unacked xmits
+ * drops to this value or lower before we start
+ * transmitting again
+ *
+ * Returns true iff the number of unacked xmits sent to
+ * the IO partition is <= low_watermark.
+ */
+static inline bool vnic_hit_low_watermark(struct visornic_devdata *devdata,
+ ulong low_watermark)
+{
+ return (devdata_xmits_outstanding(devdata) <= low_watermark);
+}
+
+/**
* visornic_xmit - send a packet to the IO Partition
* @skb: Packet to be sent
* @netdev: net device the packet is being sent from
@@ -853,13 +901,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
/* save the pointer to skb -- we'll need it for completion */
cmdrsp->net.buf = skb;
- if (((devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done) &&
- (devdata->chstat.sent_xmit - devdata->chstat.got_xmit_done >=
- devdata->max_outstanding_net_xmits)) ||
- ((devdata->chstat.sent_xmit < devdata->chstat.got_xmit_done) &&
- (ULONG_MAX - devdata->chstat.got_xmit_done +
- devdata->chstat.sent_xmit >=
- devdata->max_outstanding_net_xmits))) {
+ if (vnic_hit_high_watermark(devdata,
+ devdata->max_outstanding_net_xmits)) {
/* too many NET_XMITs queued over to IOVM - need to wait
*/
devdata->chstat.reject_count++;
@@ -941,13 +984,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
/* check to see if we have hit the high watermark for
* netif_stop_queue()
*/
- if (((devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done) &&
- (devdata->chstat.sent_xmit - devdata->chstat.got_xmit_done >=
- devdata->upper_threshold_net_xmits)) ||
- ((devdata->chstat.sent_xmit < devdata->chstat.got_xmit_done) &&
- (ULONG_MAX - devdata->chstat.got_xmit_done +
- devdata->chstat.sent_xmit >=
- devdata->upper_threshold_net_xmits))) {
+ if (vnic_hit_high_watermark(devdata,
+ devdata->upper_threshold_net_xmits)) {
/* too many NET_XMITs queued over to IOVM - need to wait */
netif_stop_queue(netdev); /* calling stop queue - call
* netif_wake_queue() after lower
@@ -1461,13 +1499,13 @@ static ssize_t info_debugfs_read(struct file *file, char __user *buf,
" num_rcv_bufs = %d\n",
devdata->num_rcv_bufs);
str_pos += scnprintf(vbuf + str_pos, len - str_pos,
- " max_oustanding_next_xmits = %d\n",
+ " max_oustanding_next_xmits = %lu\n",
devdata->max_outstanding_net_xmits);
str_pos += scnprintf(vbuf + str_pos, len - str_pos,
- " upper_threshold_net_xmits = %d\n",
+ " upper_threshold_net_xmits = %lu\n",
devdata->upper_threshold_net_xmits);
str_pos += scnprintf(vbuf + str_pos, len - str_pos,
- " lower_threshold_net_xmits = %d\n",
+ " lower_threshold_net_xmits = %lu\n",
devdata->lower_threshold_net_xmits);
str_pos += scnprintf(vbuf + str_pos, len - str_pos,
" queuefullmsg_logged = %d\n",
@@ -1566,6 +1604,9 @@ static ssize_t info_debugfs_read(struct file *file, char __user *buf,
" netif_queue = %s\n",
netif_queue_stopped(devdata->netdev) ?
"stopped" : "running");
+ str_pos += scnprintf(vbuf + str_pos, len - str_pos,
+ " xmits_outstanding = %lu\n",
+ devdata_xmits_outstanding(devdata));
}
rcu_read_unlock();
bytes_read = simple_read_from_buffer(buf, len, offset, vbuf, str_pos);
@@ -1659,16 +1700,8 @@ service_resp_queue(struct uiscmdrsp *cmdrsp, struct visornic_devdata *devdata)
* the lower watermark for
* netif_wake_queue()
*/
- if (((devdata->chstat.sent_xmit >=
- devdata->chstat.got_xmit_done) &&
- (devdata->chstat.sent_xmit -
- devdata->chstat.got_xmit_done <=
- devdata->lower_threshold_net_xmits)) ||
- ((devdata->chstat.sent_xmit <
- devdata->chstat.got_xmit_done) &&
- (ULONG_MAX - devdata->chstat.got_xmit_done
- + devdata->chstat.sent_xmit <=
- devdata->lower_threshold_net_xmits))) {
+ if (vnic_hit_low_watermark(devdata,
+ devdata->lower_threshold_net_xmits)) {
/* enough NET_XMITs completed
* so can restart netif queue
*/
@@ -1842,9 +1875,9 @@ static int visornic_probe(struct visor_device *dev)
devdata->max_outstanding_net_xmits =
max(3, ((devdata->num_rcv_bufs / 3) - 2));
devdata->upper_threshold_net_xmits =
- max(2, devdata->max_outstanding_net_xmits - 1);
+ max(2UL, (devdata->max_outstanding_net_xmits - 1));
devdata->lower_threshold_net_xmits =
- max(1, devdata->max_outstanding_net_xmits / 2);
+ max(1UL, (devdata->max_outstanding_net_xmits / 2));
skb_queue_head_init(&devdata->xmitbufhead);
--
2.1.4
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
