Re: [PATCH bpf-next 17/17] net: ti: remove rcu_read_lock() around XDP program invocation
From: Grygorii Strashko <grygorii.strashko@ti.com>
Date: 2021-06-09 17:04:35
Also in:
bpf, linux-omap
On 09/06/2021 13:33, Toke Høiland-Jørgensen wrote:
The cpsw driver has rcu_read_lock()/rcu_read_unlock() pairs around XDP program invocations. However, the actual lifetime of the objects referred by the XDP program invocation is longer, all the way through to the call to xdp_do_flush(), making the scope of the rcu_read_lock() too small. This turns out to be harmless because it all happens in a single NAPI poll cycle (and thus under local_bh_disable()), but it makes the rcu_read_lock() misleading. Rather than extend the scope of the rcu_read_lock(), just get rid of it entirely. With the addition of RCU annotations to the XDP_REDIRECT map types that take bh execution into account, lockdep even understands this to be safe, so there's really no reason to keep it around. Cc: Grygorii Strashko <grygorii.strashko@ti.com> Cc: linux-omap@vger.kernel.org Signed-off-by: Toke Høiland-Jørgensen <redacted> --- drivers/net/ethernet/ti/cpsw_priv.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)
Tested-by: Grygorii Strashko <grygorii.strashko@ti.com> Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com> -- Best regards, grygorii