staging: unisys: visornic - consolidate+simplify xmit watermark checks
The code that tests for high and low xmit watermarks was consolidatedand 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. Signed-off-by: Tim Sell <Timothy.Sell@unisys.com> Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tim Sell
Greg Kroah-Hartman
parent
cb84fca03d
commit
36927c1828
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@ -135,13 +135,14 @@ struct visornic_devdata {
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atomic_t num_rcvbuf_in_iovm;
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unsigned long alloc_failed_in_if_needed_cnt;
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unsigned long alloc_failed_in_repost_rtn_cnt;
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int max_outstanding_net_xmits; /* absolute max number of outstanding
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* xmits - should never hit this
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unsigned long max_outstanding_net_xmits; /* absolute max number of
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* outstanding xmits - should
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* never hit this
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*/
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int upper_threshold_net_xmits; /* high water mark for calling
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* netif_stop_queue()
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unsigned long upper_threshold_net_xmits; /* high water mark for
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* calling netif_stop_queue()
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*/
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int lower_threshold_net_xmits; /* high water mark for calling
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unsigned long lower_threshold_net_xmits; /* high water mark for calling
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* netif_wake_queue()
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*/
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struct sk_buff_head xmitbufhead; /* xmitbufhead is the head of the
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@ -794,6 +795,53 @@ visornic_close(struct net_device *netdev)
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return 0;
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}
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/**
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* devdata_xmits_outstanding - compute outstanding xmits
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* @devdata: visornic_devdata for device
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*
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* Return value is the number of outstanding xmits.
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*/
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static unsigned long devdata_xmits_outstanding(struct visornic_devdata *devdata)
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{
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if (devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done)
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return devdata->chstat.sent_xmit -
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devdata->chstat.got_xmit_done;
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else
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return (ULONG_MAX - devdata->chstat.got_xmit_done
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+ devdata->chstat.sent_xmit + 1);
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}
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/**
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* vnic_hit_high_watermark
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* @devdata: indicates visornic device we are checking
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* @high_watermark: max num of unacked xmits we will tolerate,
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* before we will start throttling
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*
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* Returns true iff the number of unacked xmits sent to
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* the IO partition is >= high_watermark.
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*/
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static inline bool vnic_hit_high_watermark(struct visornic_devdata *devdata,
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ulong high_watermark)
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{
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return (devdata_xmits_outstanding(devdata) >= high_watermark);
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}
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/**
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* vnic_hit_low_watermark
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* @devdata: indicates visornic device we are checking
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* @low_watermark: we will wait until the num of unacked xmits
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* drops to this value or lower before we start
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* transmitting again
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*
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* Returns true iff the number of unacked xmits sent to
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* the IO partition is <= low_watermark.
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*/
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static inline bool vnic_hit_low_watermark(struct visornic_devdata *devdata,
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ulong low_watermark)
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{
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return (devdata_xmits_outstanding(devdata) <= low_watermark);
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}
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/**
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* visornic_xmit - send a packet to the IO Partition
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* @skb: Packet to be sent
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@ -869,13 +917,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
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/* save the pointer to skb -- we'll need it for completion */
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cmdrsp->net.buf = skb;
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if (((devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done) &&
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(devdata->chstat.sent_xmit - devdata->chstat.got_xmit_done >=
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devdata->max_outstanding_net_xmits)) ||
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((devdata->chstat.sent_xmit < devdata->chstat.got_xmit_done) &&
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(ULONG_MAX - devdata->chstat.got_xmit_done +
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devdata->chstat.sent_xmit >=
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devdata->max_outstanding_net_xmits))) {
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if (vnic_hit_high_watermark(devdata,
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devdata->max_outstanding_net_xmits)) {
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/* too many NET_XMITs queued over to IOVM - need to wait
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*/
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devdata->chstat.reject_count++;
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@ -957,13 +1000,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
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/* check to see if we have hit the high watermark for
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* netif_stop_queue()
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*/
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if (((devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done) &&
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(devdata->chstat.sent_xmit - devdata->chstat.got_xmit_done >=
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devdata->upper_threshold_net_xmits)) ||
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((devdata->chstat.sent_xmit < devdata->chstat.got_xmit_done) &&
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(ULONG_MAX - devdata->chstat.got_xmit_done +
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devdata->chstat.sent_xmit >=
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devdata->upper_threshold_net_xmits))) {
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if (vnic_hit_high_watermark(devdata,
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devdata->upper_threshold_net_xmits)) {
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/* too many NET_XMITs queued over to IOVM - need to wait */
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netif_stop_queue(netdev); /* calling stop queue - call
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* netif_wake_queue() after lower
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@ -1457,13 +1495,13 @@ static ssize_t info_debugfs_read(struct file *file, char __user *buf,
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" num_rcv_bufs = %d\n",
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devdata->num_rcv_bufs);
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str_pos += scnprintf(vbuf + str_pos, len - str_pos,
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" max_oustanding_next_xmits = %d\n",
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" max_oustanding_next_xmits = %lu\n",
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devdata->max_outstanding_net_xmits);
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str_pos += scnprintf(vbuf + str_pos, len - str_pos,
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" upper_threshold_net_xmits = %d\n",
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" upper_threshold_net_xmits = %lu\n",
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devdata->upper_threshold_net_xmits);
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str_pos += scnprintf(vbuf + str_pos, len - str_pos,
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" lower_threshold_net_xmits = %d\n",
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" lower_threshold_net_xmits = %lu\n",
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devdata->lower_threshold_net_xmits);
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str_pos += scnprintf(vbuf + str_pos, len - str_pos,
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" queuefullmsg_logged = %d\n",
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@ -1562,6 +1600,9 @@ static ssize_t info_debugfs_read(struct file *file, char __user *buf,
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" netif_queue = %s\n",
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netif_queue_stopped(devdata->netdev) ?
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"stopped" : "running");
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str_pos += scnprintf(vbuf + str_pos, len - str_pos,
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" xmits_outstanding = %lu\n",
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devdata_xmits_outstanding(devdata));
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}
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rcu_read_unlock();
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bytes_read = simple_read_from_buffer(buf, len, offset, vbuf, str_pos);
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@ -1655,16 +1696,8 @@ drain_queue(struct uiscmdrsp *cmdrsp, struct visornic_devdata *devdata)
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* the lower watermark for
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* netif_wake_queue()
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*/
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if (((devdata->chstat.sent_xmit >=
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devdata->chstat.got_xmit_done) &&
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(devdata->chstat.sent_xmit -
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devdata->chstat.got_xmit_done <=
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devdata->lower_threshold_net_xmits)) ||
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((devdata->chstat.sent_xmit <
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devdata->chstat.got_xmit_done) &&
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(ULONG_MAX - devdata->chstat.got_xmit_done
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+ devdata->chstat.sent_xmit <=
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devdata->lower_threshold_net_xmits))) {
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if (vnic_hit_low_watermark(devdata,
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devdata->lower_threshold_net_xmits)) {
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/* enough NET_XMITs completed
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* so can restart netif queue
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*/
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@ -1834,12 +1867,15 @@ static int visornic_probe(struct visor_device *dev)
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/* set the net_xmit outstanding threshold */
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/* always leave two slots open but you should have 3 at a minimum */
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/* note that max_outstanding_net_xmits must be > 0 */
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devdata->max_outstanding_net_xmits =
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max(3, ((devdata->num_rcv_bufs / 3) - 2));
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max_t(unsigned long, 3, ((devdata->num_rcv_bufs / 3) - 2));
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devdata->upper_threshold_net_xmits =
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max(2, devdata->max_outstanding_net_xmits - 1);
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max_t(unsigned long,
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2, (devdata->max_outstanding_net_xmits - 1));
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devdata->lower_threshold_net_xmits =
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max(1, devdata->max_outstanding_net_xmits / 2);
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max_t(unsigned long,
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1, (devdata->max_outstanding_net_xmits / 2));
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skb_queue_head_init(&devdata->xmitbufhead);
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