net: fec: Use a spinlock to guard `fep->ptp_clk_on`

Mutexes cannot be taken in a non-preemptible context,
causing a panic in `fec_ptp_save_state()`. Replacing
`ptp_clk_mutex` by `tmreg_lock` fixes this.

Fixes: 6a4d7234ae9a ("net: fec: ptp: avoid register access when ipg clock is disabled")
Fixes: f79959220fa5 ("fec: Restart PPS after link state change")
Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/all/20220827160922.642zlcd5foopozru@pengutronix.de/
Signed-off-by: Csókás Bence <csokas.bence@prolan.hu>
Tested-by: Francesco Dolcini <francesco.dolcini@toradex.com> # Toradex Apalis iMX6
Link: https://lore.kernel.org/r/20220901140402.64804-1-csokas.bence@prolan.hu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index 20369f1..d77ee89 100644 (file)
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -561,7 +561,6 @@ struct fec_enet_private {
        struct clk *clk_2x_txclk;
 
        bool ptp_clk_on;
-       struct mutex ptp_clk_mutex;
        unsigned int num_tx_queues;
        unsigned int num_rx_queues;
 

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 111aaef..6152f6d 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -2029,6 +2029,7 @@ static void fec_enet_phy_reset_after_clk_enable(struct net_device *ndev)
 static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
 {
        struct fec_enet_private *fep = netdev_priv(ndev);
+       unsigned long flags;
        int ret;
 
        if (enable) {
@@ -2037,15 +2038,15 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
                        return ret;
 
                if (fep->clk_ptp) {
-                       mutex_lock(&fep->ptp_clk_mutex);
+                       spin_lock_irqsave(&fep->tmreg_lock, flags);
                        ret = clk_prepare_enable(fep->clk_ptp);
                        if (ret) {
-                               mutex_unlock(&fep->ptp_clk_mutex);
+                               spin_unlock_irqrestore(&fep->tmreg_lock, flags);
                                goto failed_clk_ptp;
                        } else {
                                fep->ptp_clk_on = true;
                        }
-                       mutex_unlock(&fep->ptp_clk_mutex);
+                       spin_unlock_irqrestore(&fep->tmreg_lock, flags);
                }
 
                ret = clk_prepare_enable(fep->clk_ref);
@@ -2060,10 +2061,10 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
        } else {
                clk_disable_unprepare(fep->clk_enet_out);
                if (fep->clk_ptp) {
-                       mutex_lock(&fep->ptp_clk_mutex);
+                       spin_lock_irqsave(&fep->tmreg_lock, flags);
                        clk_disable_unprepare(fep->clk_ptp);
                        fep->ptp_clk_on = false;
-                       mutex_unlock(&fep->ptp_clk_mutex);
+                       spin_unlock_irqrestore(&fep->tmreg_lock, flags);
                }
                clk_disable_unprepare(fep->clk_ref);
                clk_disable_unprepare(fep->clk_2x_txclk);
@@ -2076,10 +2077,10 @@ failed_clk_2x_txclk:
                clk_disable_unprepare(fep->clk_ref);
 failed_clk_ref:
        if (fep->clk_ptp) {
-               mutex_lock(&fep->ptp_clk_mutex);
+               spin_lock_irqsave(&fep->tmreg_lock, flags);
                clk_disable_unprepare(fep->clk_ptp);
                fep->ptp_clk_on = false;
-               mutex_unlock(&fep->ptp_clk_mutex);
+               spin_unlock_irqrestore(&fep->tmreg_lock, flags);
        }
 failed_clk_ptp:
        clk_disable_unprepare(fep->clk_enet_out);
@@ -3914,7 +3915,7 @@ fec_probe(struct platform_device *pdev)
        }
 
        fep->ptp_clk_on = false;
-       mutex_init(&fep->ptp_clk_mutex);
+       spin_lock_init(&fep->tmreg_lock);
 
        /* clk_ref is optional, depends on board */
        fep->clk_ref = devm_clk_get_optional(&pdev->dev, "enet_clk_ref");

diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
index c74d04f..8dd5a26 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_ptp.c
+++ b/drivers/net/ethernet/freescale/fec_ptp.c
@@ -365,21 +365,19 @@ static int fec_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
  */
 static int fec_ptp_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
 {
-       struct fec_enet_private *adapter =
+       struct fec_enet_private *fep =
            container_of(ptp, struct fec_enet_private, ptp_caps);
        u64 ns;
        unsigned long flags;
 
-       mutex_lock(&adapter->ptp_clk_mutex);
+       spin_lock_irqsave(&fep->tmreg_lock, flags);
        /* Check the ptp clock */
-       if (!adapter->ptp_clk_on) {
-               mutex_unlock(&adapter->ptp_clk_mutex);
+       if (!fep->ptp_clk_on) {
+               spin_unlock_irqrestore(&fep->tmreg_lock, flags);
                return -EINVAL;
        }
-       spin_lock_irqsave(&adapter->tmreg_lock, flags);
-       ns = timecounter_read(&adapter->tc);
-       spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
-       mutex_unlock(&adapter->ptp_clk_mutex);
+       ns = timecounter_read(&fep->tc);
+       spin_unlock_irqrestore(&fep->tmreg_lock, flags);
 
        *ts = ns_to_timespec64(ns);
 
@@ -404,10 +402,10 @@ static int fec_ptp_settime(struct ptp_clock_info *ptp,
        unsigned long flags;
        u32 counter;
 
-       mutex_lock(&fep->ptp_clk_mutex);
+       spin_lock_irqsave(&fep->tmreg_lock, flags);
        /* Check the ptp clock */
        if (!fep->ptp_clk_on) {
-               mutex_unlock(&fep->ptp_clk_mutex);
+               spin_unlock_irqrestore(&fep->tmreg_lock, flags);
                return -EINVAL;
        }
 
@@ -417,11 +415,9 @@ static int fec_ptp_settime(struct ptp_clock_info *ptp,
         */
        counter = ns & fep->cc.mask;
 
-       spin_lock_irqsave(&fep->tmreg_lock, flags);
        writel(counter, fep->hwp + FEC_ATIME);
        timecounter_init(&fep->tc, &fep->cc, ns);
        spin_unlock_irqrestore(&fep->tmreg_lock, flags);
-       mutex_unlock(&fep->ptp_clk_mutex);
        return 0;
 }
 
@@ -518,13 +514,11 @@ static void fec_time_keep(struct work_struct *work)
        struct fec_enet_private *fep = container_of(dwork, struct fec_enet_private, time_keep);
        unsigned long flags;
 
-       mutex_lock(&fep->ptp_clk_mutex);
+       spin_lock_irqsave(&fep->tmreg_lock, flags);
        if (fep->ptp_clk_on) {
-               spin_lock_irqsave(&fep->tmreg_lock, flags);
                timecounter_read(&fep->tc);
-               spin_unlock_irqrestore(&fep->tmreg_lock, flags);
        }
-       mutex_unlock(&fep->ptp_clk_mutex);
+       spin_unlock_irqrestore(&fep->tmreg_lock, flags);
 
        schedule_delayed_work(&fep->time_keep, HZ);
 }
@@ -599,8 +593,6 @@ void fec_ptp_init(struct platform_device *pdev, int irq_idx)
        }
        fep->ptp_inc = NSEC_PER_SEC / fep->cycle_speed;
 
-       spin_lock_init(&fep->tmreg_lock);
-
        fec_ptp_start_cyclecounter(ndev);
 
        INIT_DELAYED_WORK(&fep->time_keep, fec_time_keep);