Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756038Ab3CZWwR (ORCPT ); Tue, 26 Mar 2013 18:52:17 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52963 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751939Ab3CZWwN (ORCPT ); Tue, 26 Mar 2013 18:52:13 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ben Hutchings Subject: [ 22/72] sfc: Fix timekeeping in efx_mcdi_poll() Date: Tue, 26 Mar 2013 15:51:05 -0700 Message-Id: <20130326224921.993605629@linuxfoundation.org> X-Mailer: git-send-email 1.8.1.rc1.5.g7e0651a In-Reply-To: <20130326224919.675227837@linuxfoundation.org> References: <20130326224919.675227837@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3212 Lines: 94 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings [ Upstream commit ebf98e797b4e26ad52ace1511a0b503ee60a6cd4 ] efx_mcdi_poll() uses get_seconds() to read the current time and to implement a polling timeout. The use of this function was chosen partly because it could easily be replaced in a co-sim environment with a macro that read the simulated time. Unfortunately the real get_seconds() returns the system time (real time) which is subject to adjustment by e.g. ntpd. If the system time is adjusted forward during a polled MCDI operation, the effective timeout can be shorter than the intended 10 seconds, resulting in a spurious failure. It is also possible for a backward adjustment to delay detection of a areal failure. Use jiffies instead, and change MCDI_RPC_TIMEOUT to be denominated in jiffies. Also correct rounding of the timeout: check time > finish (or rather time_after(time, finish)) and not time >= finish. Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/sfc/mcdi.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/drivers/net/ethernet/sfc/mcdi.c +++ b/drivers/net/ethernet/sfc/mcdi.c @@ -22,7 +22,7 @@ ************************************************************************** */ -#define MCDI_RPC_TIMEOUT 10 /*seconds */ +#define MCDI_RPC_TIMEOUT (10 * HZ) #define MCDI_PDU(efx) \ (efx_port_num(efx) ? MC_SMEM_P1_PDU_OFST : MC_SMEM_P0_PDU_OFST) @@ -120,7 +120,7 @@ static void efx_mcdi_copyout(struct efx_ static int efx_mcdi_poll(struct efx_nic *efx) { struct efx_mcdi_iface *mcdi = efx_mcdi(efx); - unsigned int time, finish; + unsigned long time, finish; unsigned int respseq, respcmd, error; unsigned int pdu = FR_CZ_MC_TREG_SMEM + MCDI_PDU(efx); unsigned int rc, spins; @@ -136,7 +136,7 @@ static int efx_mcdi_poll(struct efx_nic * and poll once a jiffy (approximately) */ spins = TICK_USEC; - finish = get_seconds() + MCDI_RPC_TIMEOUT; + finish = jiffies + MCDI_RPC_TIMEOUT; while (1) { if (spins != 0) { @@ -146,7 +146,7 @@ static int efx_mcdi_poll(struct efx_nic schedule_timeout_uninterruptible(1); } - time = get_seconds(); + time = jiffies; rmb(); efx_readd(efx, ®, pdu); @@ -158,7 +158,7 @@ static int efx_mcdi_poll(struct efx_nic EFX_DWORD_FIELD(reg, MCDI_HEADER_RESPONSE)) break; - if (time >= finish) + if (time_after(time, finish)) return -ETIMEDOUT; } @@ -250,7 +250,7 @@ static int efx_mcdi_await_completion(str if (wait_event_timeout( mcdi->wq, atomic_read(&mcdi->state) == MCDI_STATE_COMPLETED, - msecs_to_jiffies(MCDI_RPC_TIMEOUT * 1000)) == 0) + MCDI_RPC_TIMEOUT) == 0) return -ETIMEDOUT; /* Check if efx_mcdi_set_mode() switched us back to polled completions. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/