On Wed, Aug 31, 2022 at 04:21:47PM +0200, Csókás Bence wrote:

On 2022. 08. 31. 16:03, Andrew Lunn wrote:

quoted

quoted

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index b0d60f898249..98d8f8d6034e 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c

@@ -2029,6 +2029,7 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
  {
  	struct fec_enet_private *fep = netdev_priv(ndev);
  	int ret;
+	unsigned long flags;

Please keep to reverse christmas tree

checkpatch didn't tell me that was a requirement... Easy to fix though.

checkpatch does not have the smarts to detect this. And it is a netdev
only thing.

quoted

quoted

  	if (enable) {
  		ret = clk_prepare_enable(fep->clk_enet_out);

@@ -2036,15 +2037,15 @@ 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->ptp_clk_lock, flags);

Is the ptp hardware accessed in interrupt context? If not, you can use
a plain spinlock, not _irqsave..

`fec_suspend()` calls `fec_enet_clk_enable()`, which may be a
non-preemptible context, I'm not sure how the PM subsystem's internals
work...
Besides, with the way this driver is built, function call dependencies all
over the place, I think it's better safe than sorry. I don't think there is
any disadvantage (besides maybe a few lost cycles) of using _irqsave in
regular process context anyways.

Those using real time will probably disagree.

There is also a different between not being able to sleep, and not
being able to process an interrupt for some other hardware. You got a
report about taking a mutex in atomic context. That just means you
cannot sleep, probably because a spinlock is held. That is very
different to not being able to handle interrupts. You only need
spin_lock_irqsave() if the interrupt handler also needs the same spin
lock to protect it from a thread using the spin lock.

     Andrew