Commit 6344f052 authored by Mark Brown's avatar Mark Brown Committed by David S. Miller
Browse files

natsemi: Update locking documentation 



The documentation regarding synchronisation at the head of the natsemi
driver was badly bitrotted so replace it with a general statement about
the techniques used which is less likely to bitrot.

Also remove the note saying these chips are uncommon - it makes little
difference but they were used in a number of laptops and at least one mass
market PCI ethernet card.

Signed-off-by: default avatarMark Brown <broonie@sirena.org.uk>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 35b5f6b1

drivers/net/natsemi.c

+2 −16
Original line number Diff line number Diff line
@@ -203,22 +203,8 @@ skbuff at an offset of "+2", 16-byte aligning the IP header. 
IIId. Synchronization



Most operations are synchronized on the np->lock irq spinlock, except the

performance critical codepaths:



The rx process only runs in the interrupt handler. Access from outside

the interrupt handler is only permitted after disable_irq().



The rx process usually runs under the netif_tx_lock. If np->intr_tx_reap

is set, then access is permitted under spin_lock_irq(&np->lock).



Thus configuration functions that want to access everything must call

	disable_irq(dev->irq);

	netif_tx_lock_bh(dev);

	spin_lock_irq(&np->lock);



IV. Notes



NatSemi PCI network controllers are very uncommon.

recieve and transmit paths which are synchronised using a combination of

hardware descriptor ownership, disabling interrupts and NAPI poll scheduling.



IVb. References