Andrew Vasquez wrote:
On Tue, 15 Aug 2006, Vladislav Bolkhovitin wrote:
Looking at the qla2xxx driver source code I noticed that
scsi_qla_host_t.fcports is used without any protection. For instance,
qla2x00_loop_reset() walks over this list. This function is called from
qla2xxx_eh_bus_reset(), which could be called at any time. What does
protect fcports from being changed, eg, by some async loop event during
the walking and eventually oops'ing? Do I miss something? There are many
such unprotected fcports list usages in the driver.
Nothing is ever removed from the fcports list during driver execution.
fcports are also only added from a single context (post init-time)
within the DPC thread. We are safe here.
Sorry, I don't think so. For lockless iterating over a list concurrently
with the addition to it you need to use *_rcu() list functions and do
some RCU locking or, at least, disable preemption. Otherwise it is not safe.
Also, I don't think that keeping dead FC ports entries forever is a good
idea. What does prevent you from deleting them, for instance, after
fc_remote_port_delete() call?
Vlad
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