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| author | Julian Wiedmann <jwi@linux.vnet.ibm.com> | 2018-02-27 18:58:12 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-02-28 11:13:12 -0500 |
| commit | 12472af89632beb1ed8dea29d4efe208ca05b06a (patch) | |
| tree | 7ff331b71a1d91c8614d0c7630cd8deba11c83bc | |
| parent | 590399ddf9561f2ed0839311c8ae1be21597ba68 (diff) | |
| download | blackbird-obmc-linux-12472af89632beb1ed8dea29d4efe208ca05b06a.tar.gz blackbird-obmc-linux-12472af89632beb1ed8dea29d4efe208ca05b06a.zip | |
s390/qeth: fix overestimated count of buffer elements
qeth_get_elements_for_range() doesn't know how to handle a 0-length
range (ie. start == end), and returns 1 when it should return 0.
Such ranges occur on TSO skbs, where the L2/L3/L4 headers (and thus all
of the skb's linear data) are skipped when mapping the skb into regular
buffer elements.
This overestimation may cause several performance-related issues:
1. sub-optimal IO buffer selection, where the next buffer gets selected
even though the skb would actually still fit into the current buffer.
2. forced linearization, if the element count for a non-linear skb
exceeds QETH_MAX_BUFFER_ELEMENTS.
Rather than modifying qeth_get_elements_for_range() and adding overhead
to every caller, fix up those callers that are in risk of passing a
0-length range.
Fixes: 2863c61334aa ("qeth: refactor calculation of SBALE count")
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/s390/net/qeth_core_main.c | 10 | ||||
| -rw-r--r-- | drivers/s390/net/qeth_l3_main.c | 11 |
2 files changed, 12 insertions, 9 deletions
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c index ca72f3311004..30457fca30c5 100644 --- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -3898,10 +3898,12 @@ EXPORT_SYMBOL_GPL(qeth_get_elements_for_frags); int qeth_get_elements_no(struct qeth_card *card, struct sk_buff *skb, int extra_elems, int data_offset) { - int elements = qeth_get_elements_for_range( - (addr_t)skb->data + data_offset, - (addr_t)skb->data + skb_headlen(skb)) + - qeth_get_elements_for_frags(skb); + addr_t end = (addr_t)skb->data + skb_headlen(skb); + int elements = qeth_get_elements_for_frags(skb); + addr_t start = (addr_t)skb->data + data_offset; + + if (start != end) + elements += qeth_get_elements_for_range(start, end); if ((elements + extra_elems) > QETH_MAX_BUFFER_ELEMENTS(card)) { QETH_DBF_MESSAGE(2, "Invalid size of IP packet " diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c index b0c888e86cd4..3421893c37a4 100644 --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -2450,11 +2450,12 @@ static void qeth_tso_fill_header(struct qeth_card *card, static int qeth_l3_get_elements_no_tso(struct qeth_card *card, struct sk_buff *skb, int extra_elems) { - addr_t tcpdptr = (addr_t)tcp_hdr(skb) + tcp_hdrlen(skb); - int elements = qeth_get_elements_for_range( - tcpdptr, - (addr_t)skb->data + skb_headlen(skb)) + - qeth_get_elements_for_frags(skb); + addr_t start = (addr_t)tcp_hdr(skb) + tcp_hdrlen(skb); + addr_t end = (addr_t)skb->data + skb_headlen(skb); + int elements = qeth_get_elements_for_frags(skb); + + if (start != end) + elements += qeth_get_elements_for_range(start, end); if ((elements + extra_elems) > QETH_MAX_BUFFER_ELEMENTS(card)) { QETH_DBF_MESSAGE(2, |
