3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>
[ 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 <bhutchings@xxxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/net/ethernet/sfc/mcdi.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index 85e070e..c1000ce 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -30,7 +30,7 @@
#define REBOOT_FLAG_PORT0 0x3f8
#define REBOOT_FLAG_PORT1 0x3fc
-#define MCDI_RPC_TIMEOUT 10 /*seconds */
+#define MCDI_RPC_TIMEOUT (10 * HZ)
#define MCDI_PDU(efx) \
(efx_port_num(efx) ? CMD_PDU_PORT1 : CMD_PDU_PORT0)
@@ -120,7 +120,7 @@ static void efx_mcdi_copyout(struct efx_nic *efx, u8 *outbuf, size_t outlen)
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 *efx)
* 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 *efx)
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)
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(struct efx_nic *efx)
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.
--
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