Hi experts
I am hoping for some guidance.
Does DSA offer any protection against concurrent calls of dsa_switch_ops?
I did not include any locking in the code I contributed to lan9303.
First I felt bad locking is worse than no locking. Second I assumed that
reviewers would point out if locking is needed.
The most "interesting" part of the lan9303 driver that has no locking is
the ALR (=fdb/mdb). ALR access is a sequence of register operations.
Anyway it is very unlikely that mdb related calls are reentered. But if
it can happen, it would mean that IGMP snooping can go wrong. (Which is
actually very bad in our applications.)
Is this something to worry about?
If yes, what is the best strategy to deal with it?
Looking in drivers/net/dsa/lan9303-core.c :
lan9303_indirect_phy_read/lan9303_indirect_phy_write +
lan9303_write_switch_reg/lan9303_read_switch_reg are already protected
by chip->indirect_mutex
ALR access uses lan9303_write_switch_reg/lan9303_read_switch_reg.
Adding a chip->alr_mutex on top of chip->indirect_mutex does not feel
right to me. Would it be better to move the locking up to the relevant
dsa_switch_ops functions?
Thanks
Egil Hjelmeland
