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ionic: avoid races in ionic_heartbeat_check 

Rework the heartbeat checks to be sure that we're getting an
atomic operation.  Through testing we found occasions where a
separate thread could clash with this check and cause erroneous
heartbeat check results.

Signed-off-by: Allen Hubbe <allenbh@pensando.io>
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Shannon Nelson 2021-03-30 12:52:09 -07:00 committed by David S. Miller
parent 230efff47a
commit b2b9a8d7ed
2 changed files with 63 additions and 37 deletions
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93
drivers/net/ethernet/pensando/ionic/ionic_dev.c
View File

@ -24,6 +24,9 @@ static void ionic_watchdog_cb(struct timer_list *t)
return;
hb = ionic_heartbeat_check(ionic);
dev_dbg(ionic->dev, "%s: hb %d running %d UP %d\n",
__func__, hb, netif_running(lif->netdev),
test_bit(IONIC_LIF_F_UP, lif->state));
if (hb >= 0 &&
!test_bit(IONIC_LIF_F_FW_RESET, lif->state))
@ -91,9 +94,17 @@ int ionic_dev_setup(struct ionic *ionic)
return -EFAULT;
}
idev->last_fw_status = 0xff;
timer_setup(&ionic->watchdog_timer, ionic_watchdog_cb, 0);
ionic->watchdog_period = IONIC_WATCHDOG_SECS * HZ;
/* set times to ensure the first check will proceed */
atomic_long_set(&idev->last_check_time, jiffies - 2 * HZ);
idev->last_hb_time = jiffies - 2 * ionic->watchdog_period;
/* init as ready, so no transition if the first check succeeds */
idev->last_fw_hb = 0;
idev->fw_hb_ready = true;
idev->fw_status_ready = true;
mod_timer(&ionic->watchdog_timer,
round_jiffies(jiffies + ionic->watchdog_period));
@ -107,29 +118,38 @@ int ionic_dev_setup(struct ionic *ionic)
int ionic_heartbeat_check(struct ionic *ionic)
{
struct ionic_dev *idev = &ionic->idev;
unsigned long hb_time;
unsigned long check_time, last_check_time;
bool fw_status_ready, fw_hb_ready;
u8 fw_status;
u32 hb;
u32 fw_hb;
/* wait a little more than one second before testing again */
hb_time = jiffies;
if (time_before(hb_time, (idev->last_hb_time + ionic->watchdog_period)))
/* wait a least one second before testing again */
check_time = jiffies;
last_check_time = atomic_long_read(&idev->last_check_time);
do_check_time:
if (time_before(check_time, last_check_time + HZ))
return 0;
if (!atomic_long_try_cmpxchg_relaxed(&idev->last_check_time,
&last_check_time, check_time)) {
/* if called concurrently, only the first should proceed. */
dev_dbg(ionic->dev, "%s: do_check_time again\n", __func__);
goto do_check_time;
}
/* firmware is useful only if the running bit is set and
* fw_status != 0xff (bad PCI read)
*/
fw_status = ioread8(&idev->dev_info_regs->fw_status);
if (fw_status != 0xff)
fw_status &= IONIC_FW_STS_F_RUNNING; /* use only the run bit */
fw_status_ready = (fw_status != 0xff) && (fw_status & IONIC_FW_STS_F_RUNNING);
/* is this a transition? */
if (fw_status != idev->last_fw_status &&
idev->last_fw_status != 0xff) {
if (fw_status_ready != idev->fw_status_ready) {
struct ionic_lif *lif = ionic->lif;
bool trigger = false;
if (!fw_status || fw_status == 0xff) {
idev->fw_status_ready = fw_status_ready;
if (!fw_status_ready) {
dev_info(ionic->dev, "FW stopped %u\n", fw_status);
if (lif && !test_bit(IONIC_LIF_F_FW_RESET, lif->state))
trigger = true;
@ -143,44 +163,47 @@ int ionic_heartbeat_check(struct ionic *ionic)
struct ionic_deferred_work *work;
work = kzalloc(sizeof(*work), GFP_ATOMIC);
if (!work) {
dev_err(ionic->dev, "LIF reset trigger dropped\n");
} else {
if (work) {
work->type = IONIC_DW_TYPE_LIF_RESET;
if (fw_status & IONIC_FW_STS_F_RUNNING &&
fw_status != 0xff)
work->fw_status = 1;
work->fw_status = fw_status_ready;
ionic_lif_deferred_enqueue(&lif->deferred, work);
}
}
}
idev->last_fw_status = fw_status;
if (!fw_status || fw_status == 0xff)
if (!fw_status_ready)
return -ENXIO;
/* early FW has no heartbeat, else FW will return non-zero */
hb = ioread32(&idev->dev_info_regs->fw_heartbeat);
if (!hb)
/* wait at least one watchdog period since the last heartbeat */
last_check_time = idev->last_hb_time;
if (time_before(check_time, last_check_time + ionic->watchdog_period))
return 0;
/* are we stalled? */
if (hb == idev->last_hb) {
/* only complain once for each stall seen */
if (idev->last_hb_time != 1) {
dev_info(ionic->dev, "FW heartbeat stalled at %d\n",
idev->last_hb);
idev->last_hb_time = 1;
}
fw_hb = ioread32(&idev->dev_info_regs->fw_heartbeat);
fw_hb_ready = fw_hb != idev->last_fw_hb;
return -ENXIO;
/* early FW version had no heartbeat, so fake it */
if (!fw_hb_ready && !fw_hb)
fw_hb_ready = true;
dev_dbg(ionic->dev, "%s: fw_hb %u last_fw_hb %u ready %u\n",
__func__, fw_hb, idev->last_fw_hb, fw_hb_ready);
idev->last_fw_hb = fw_hb;
/* log a transition */
if (fw_hb_ready != idev->fw_hb_ready) {
idev->fw_hb_ready = fw_hb_ready;
if (!fw_hb_ready)
dev_info(ionic->dev, "FW heartbeat stalled at %d\n", fw_hb);
else
dev_info(ionic->dev, "FW heartbeat restored at %d\n", fw_hb);
}
if (idev->last_hb_time == 1)
dev_info(ionic->dev, "FW heartbeat restored at %d\n", hb);
if (!fw_hb_ready)
return -ENXIO;
idev->last_hb = hb;
idev->last_hb_time = hb_time;
idev->last_hb_time = check_time;
return 0;
}

7
drivers/net/ethernet/pensando/ionic/ionic_dev.h
View File

@ -4,6 +4,7 @@
#ifndef _IONIC_DEV_H_
#define _IONIC_DEV_H_
#include <linux/atomic.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
@ -135,9 +136,11 @@ struct ionic_dev {
union ionic_dev_info_regs __iomem *dev_info_regs;
union ionic_dev_cmd_regs __iomem *dev_cmd_regs;
atomic_long_t last_check_time;
unsigned long last_hb_time;
u32 last_hb;
u8 last_fw_status;
u32 last_fw_hb;
bool fw_hb_ready;
bool fw_status_ready;
u64 __iomem *db_pages;
dma_addr_t phy_db_pages;