net: dsa: mv88e6xxx: Fix interrupt masking on removal

When removing the interrupt handling code, we should mask the
generation of interrupts. The code however unmasked all
interrupts. This can then cause a new interrupt. We then get into a
deadlock where the interrupt thread is waiting to run, and the code
continues, trying to remove the interrupt handler, which means waiting
for the thread to complete. On a UP machine this deadlocks.

Fix so we really mask interrupts in the hardware. The same error is
made in the error path when install the interrupt handling code.

Fixes: 3460a5770ce9 ("net: dsa: mv88e6xxx: Mask g1 interrupts and free interrupt")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -339,7 +339,7 @@ static void mv88e6xxx_g1_irq_free(struct mv88e6xxx_chip *chip)
 	u16 mask;
 
 	mv88e6xxx_g1_read(chip, MV88E6XXX_G1_CTL1, &mask);
-	mask |= GENMASK(chip->g1_irq.nirqs, 0);
+	mask &= ~GENMASK(chip->g1_irq.nirqs, 0);
 	mv88e6xxx_g1_write(chip, MV88E6XXX_G1_CTL1, mask);
 
 	free_irq(chip->irq, chip);
@@ -395,7 +395,7 @@ static int mv88e6xxx_g1_irq_setup(struct mv88e6xxx_chip *chip)
 	return 0;
 
 out_disable:
-	mask |= GENMASK(chip->g1_irq.nirqs, 0);
+	mask &= ~GENMASK(chip->g1_irq.nirqs, 0);
 	mv88e6xxx_g1_write(chip, MV88E6XXX_G1_CTL1, mask);
 
 out_mapping: