Commit b2b9a8d7 authored by Shannon Nelson's avatar Shannon Nelson Committed by David S. Miller
Browse files

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: default avatarAllen Hubbe <allenbh@pensando.io>
Signed-off-by: default avatarShannon Nelson <snelson@pensando.io>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 230efff4

drivers/net/ethernet/pensando/ionic/ionic_dev.c

+58 −35
Original line number Diff line number Diff line
@@ -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;

}

drivers/net/ethernet/pensando/ionic/ionic_dev.h

+5 −2
Original line number Diff line number Diff line
@@ -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;