Re: [LKP] rcu_read_lock lost its compiler barrier
- First Post
- Replies
- Stats
-
Go to
- ----- 2022 -----
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2021 -----
- December
- November
- October
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2020 -----
- December
- November
- October
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2019 -----
- December
- November
- October
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2018 -----
- December
- November
- October
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2017 -----
- December
- November
- October
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2016 -----
- December
- November
- October
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2015 -----
- December
- November
- October
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2014 -----
- December
- November
- October
- September
- August
- July
- June
- May
- April
- March
- February
- January
- ----- 2013 -----
- December
- November
- October
- September
- August
On Thu, Jun 06, 2019 at 02:06:19AM -0700, Paul E. McKenney wrote:
Or is your point instead that given the initial value of "a" being
zero and the value stored to "a" being one, there is no way that
any possible load and store tearing (your slicing and dicing) could
possibly mess up the test of the value loaded from "a"?
Exactly. If you can dream up of a scenario where the compiler can
get this wrong I'm all ears.
> But I do concede that in the general RCU case you must have the
> READ_ONCE/WRITE_ONCE calls for rcu_dereference/rcu_assign_pointer.
OK, good that we are in agreement on this part, at least! ;-)
Well only because we're allowing crazy compilers that can turn
a simple word-aligned word assignment (a = b) into two stores.
Cheers,
--
Email: Herbert Xu <herbert(a)gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
1200
days inactive
1200
days old
0 comments
1 participants
tags (0)
participants (1)
-
Herbert Xu