Commit 89271c65 authored by Ursula Braun's avatar Ursula Braun Committed by David S. Miller

s390/qeth: fix underestimated count of buffer elements

For a memory range/skb where the last byte falls onto a page boundary
(ie. 'end' is of the form xxx...xxx001), the PFN_UP() part of the
calculation currently doesn't round up to the next PFN due to an
off-by-one error.
Thus qeth believes that the skb occupies one page less than it
actually does, and may select a IO buffer that doesn't have enough spare
buffer elements to fit all of the skb's data.
HW detects this as a malformed buffer descriptor, and raises an
exception which then triggers device recovery.

Fixes: 2863c613 ("qeth: refactor calculation of SBALE count")
Signed-off-by: default avatarUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: default avatarJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0bf7800f
...@@ -846,7 +846,7 @@ struct qeth_trap_id { ...@@ -846,7 +846,7 @@ struct qeth_trap_id {
*/ */
static inline int qeth_get_elements_for_range(addr_t start, addr_t end) static inline int qeth_get_elements_for_range(addr_t start, addr_t end)
{ {
return PFN_UP(end - 1) - PFN_DOWN(start); return PFN_UP(end) - PFN_DOWN(start);
} }
static inline int qeth_get_micros(void) static inline int qeth_get_micros(void)
......
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