4.9-stable review patch. If anyone has any objections, please let me know.
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From: Ursula Braun ubraun@linux.vnet.ibm.com
[ Upstream commit 89271c65edd599207dd982007900506283c90ae3 ]
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: 2863c61334aa ("qeth: refactor calculation of SBALE count") Signed-off-by: Ursula Braun ubraun@linux.vnet.ibm.com Signed-off-by: Julian Wiedmann jwi@linux.vnet.ibm.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/s390/net/qeth_core.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -849,7 +849,7 @@ struct qeth_trap_id { */ 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)