On 7/20/2017 3:28 AM, Håkon Bugge wrote:
cp->cp_send_gen is treated as a normal variable, although it may be
used by different threads.
This is fixed by using {READ,WRITE}_ONCE when it is incremented and
READ_ONCE when it is read outside the {acquire,release}_in_xmit
protection.
There is explicit memory barrier before the value is read outside
the {acquire,release}_in_xmit so it takes care of load/store sync.
Normative reference from the Linux-Kernel Memory Model:
Loads from and stores to shared (but non-atomic) variables should
be protected with the READ_ONCE(), WRITE_ONCE(), and
ACCESS_ONCE().
Clause 5.1.2.4/25 in the C standard is also relevant.
Signed-off-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
Reviewed-by: Knut Omang <knut.omang@xxxxxxxxxx>
---
Having said that, {READ,WRITE}_ONCE usages seems to make
it clear and explicit. So its fine with me.
Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx>
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