netdev - Re: [PATCH net-next v4] net/smc: remove unneeded atomic operations in smc_tx_sndbuf

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Date: Fri, 24 Nov 2023 13:55:05 +0100
From: Wenjia Zhang <wenjia@...ux.ibm.com>
To: Li RongQing <lirongqing@...du.com>, linux-s390@...r.kernel.org,
        netdev@...r.kernel.org, wintera@...ux.ibm.com,
        dust.li@...ux.alibaba.com
Subject: Re: [PATCH net-next v4] net/smc: remove unneeded atomic operations in
 smc_tx_sndbuf_nonempty



On 23.11.23 02:45, Li RongQing wrote:
> The commit dcd2cf5f2fc0 ("net/smc: add autocorking support") adds an
> atomic variable tx_pushing in smc_connection to make sure only one can
> send to let it cork more and save CDC slot. since smc_tx_pending can be
> called in the soft IRQ without checking sock_owned_by_user() at that
> time, which would cause a race condition because bh_lock_sock() did
> not honor sock_lock()
> 
> After commit 6b88af839d20 ("net/smc: don't send in the BH context if
> sock_owned_by_user"), the transmission is deferred to when sock_lock()
> is held by the user. Therefore, we no longer need tx_pending to hold
> message.
> 
> So remove atomic variable tx_pushing and its operation, and
> smc_tx_sndbuf_nonempty becomes a wrapper of __smc_tx_sndbuf_nonempty,
> so rename __smc_tx_sndbuf_nonempty back to smc_tx_sndbuf_nonempty
> 
> Suggested-by: Alexandra Winter <wintera@...ux.ibm.com>
> Co-developed-by: Dust Li <dust.li@...ux.alibaba.com>
> Signed-off-by: Dust Li <dust.li@...ux.alibaba.com>
> Signed-off-by: Li RongQing <lirongqing@...du.com>
> ---

To the patch, LGTM! Again, please copy the related subsystem maintainers 
explicitly!

Reviewed-and-tested-by: Wenjia Zhang <wenjia@...ux.ibm.com>