Re: [PATCH 1/2] Revert "net: fec: Use a spinlock to guard `fep->ptp_clk_on`"

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 12.09.2022 07:31:04, Bence Csókás wrote:
> From: Csókás Bence <csokas.bence@prolan.hu>
> 
> `clk_prepare_enable()` gets called in atomic context (holding a spinlock),
> which may sleep, causing a BUG on certain platforms.
> 
> This reverts commit b353b241f1eb9b6265358ffbe2632fdcb563354f.
> 
> Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
> Link: https://lore.kernel.org/all/20220907143915.5w65kainpykfobte@pengutronix.de/
> Signed-off-by: Csókás Bence <csokas.bence@prolan.hu>

This is not a 100% revert.

In b353b241f1eb ("net: fec: Use a spinlock to guard `fep->ptp_clk_on`")
the "struct fec_enet_private *fep" was renamed to "struct
fec_enet_private *adapter" for no apparent reason. The driver uses "fep"
everywhere else. This revert doesn't restore the original state.

This leads to the following diff against a 100% revert.

diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
index c99dff3c3422..c74d04f4b2fd 100644
--- a/drivers/net/ethernet/freescale/fec_ptp.c
+++ b/drivers/net/ethernet/freescale/fec_ptp.c
@@ -365,21 +365,21 @@ 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 *fep =
+       struct fec_enet_private *adapter =
            container_of(ptp, struct fec_enet_private, ptp_caps);
        u64 ns;
        unsigned long flags;
 
-       mutex_lock(&fep->ptp_clk_mutex);
+       mutex_lock(&adapter->ptp_clk_mutex);
        /* Check the ptp clock */
-       if (!fep->ptp_clk_on) {
-               mutex_unlock(&fep->ptp_clk_mutex);
+       if (!adapter->ptp_clk_on) {
+               mutex_unlock(&adapter->ptp_clk_mutex);
                return -EINVAL;
        }
-       spin_lock_irqsave(&fep->tmreg_lock, flags);
-       ns = timecounter_read(&fep->tc);
-       spin_unlock_irqrestore(&fep->tmreg_lock, flags);
-       mutex_unlock(&fep->ptp_clk_mutex);
+       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);
 
        *ts = ns_to_timespec64(ns);

regards,
Marc

-- 
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