From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dennis Dalessandro Subject: [PATCH for-next 1/2] IB/rdmavt: Setting of QP timeout can overflow jiffies computation Date: Sat, 17 Jun 2017 10:37:26 -0700 Message-ID: <20170617173723.17658.85726.stgit@scvm10.sc.intel.com> References: <20170617173620.17658.5173.stgit@scvm10.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170617173620.17658.5173.stgit-9QXIwq+3FY+1XWohqUldA0EOCMrvLtNR@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mike Marciniszyn , Kaike Wan List-Id: linux-rdma@vger.kernel.org From: Kaike Wan Current computation of qp->timeout_jiffies in rvt_modify_qp() will cause overflow due to the fact that the input to the function usecs_to_jiffies is only 32-bit ( unsigned int). Overflow will occur when attr->timeout is equal to or greater than 30. The consequence is unnecessarily excessive retry and thus degradation of the system performance. This patch fixes the problem by limiting the input to 5-bit and calling usecs_to_jiffies() before multiplying the scaling factor. Reviewed-by: Mike Marciniszyn Signed-off-by: Kaike Wan Signed-off-by: Dennis Dalessandro --- drivers/infiniband/sw/rdmavt/qp.c | 4 +--- include/rdma/rdmavt_qp.h | 14 ++++++++++++++ 2 files changed, 15 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c index 2ce0928..17b2eb0 100644 --- a/drivers/infiniband/sw/rdmavt/qp.c +++ b/drivers/infiniband/sw/rdmavt/qp.c @@ -1284,9 +1284,7 @@ int rvt_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr, if (attr_mask & IB_QP_TIMEOUT) { qp->timeout = attr->timeout; - qp->timeout_jiffies = - usecs_to_jiffies((4096UL * (1UL << qp->timeout)) / - 1000UL); + qp->timeout_jiffies = rvt_timeout_to_jiffies(qp->timeout); } if (attr_mask & IB_QP_QKEY) diff --git a/include/rdma/rdmavt_qp.h b/include/rdma/rdmavt_qp.h index 13f43b3..07e2fff 100644 --- a/include/rdma/rdmavt_qp.h +++ b/include/rdma/rdmavt_qp.h @@ -647,6 +647,20 @@ static inline u32 rvt_div_mtu(struct rvt_qp *qp, u32 len) return len >> qp->log_pmtu; } +/** + * rvt_timeout_to_jiffies - Convert a ULP timeout input into jiffies + * @timeout - timeout input(0 - 31). + * + * Return a timeout value in jiffies. + */ +static inline unsigned long rvt_timeout_to_jiffies(u8 timeout) +{ + if (timeout > 31) + timeout = 31; + + return usecs_to_jiffies(1U << timeout) * 4096UL / 1000UL; +} + extern const int ib_rvt_state_ops[]; struct rvt_dev_info; -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html