[ Upstream commit 1a77557d48cff187a169c2aec01c0dd78a5e7e50 ]
When under heavy load, network processing can run CPU-bound for many
tens of seconds. Even in preemptible kernels (non-RT kernel), this can
block RCU Tasks grace periods, which can cause trace-event removal to
take more than a minute, which is unacceptably long.
This commit therefore creates a new helper function that passes through
both RCU and RCU-Tasks quiescent states every 100 milliseconds. This
hard-coded value suffices for current workloads.
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Jesper Dangaard Brouer <hawk@kernel.org>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/r/90431d46ee112d2b0af04dbfe936faaca11810a5.1710877680.git.yan@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 00bf63122459 ("bpf: report RCU QS in cpumap kthread")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e6c86c513f440bec5f1046539c7e3c6c653842da ]
As an accident of implementation, an RCU Tasks Trace grace period also
acts as an RCU grace period. However, this could change at any time.
This commit therefore creates an rcu_trace_implies_rcu_gp() that currently
returns true to codify this accident. Code relying on this accident
must call this function to verify that this accident is still happening.
Reported-by: Hou Tao <houtao@huaweicloud.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Link: https://lore.kernel.org/r/20221014113946.965131-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 876673364161 ("bpf: Defer the free of inner map when necessary")
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 10108826191ab30388e8ae9d54505a628f78a7ec)
Signed-off-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 76c8eaafe4f061f3790112842a2fbb297e4bea88 ]
The xchg() and cmpxchg() functions are sometimes used to carry out RCU
updates. Unfortunately, this can result in sparse warnings for both
the old-value and new-value arguments, as well as for the return value.
The arguments can be dealt with using RCU_INITIALIZER():
old_p = xchg(&p, RCU_INITIALIZER(new_p));
But a sparse warning still remains due to assigning the __rcu pointer
returned from xchg to the (most likely) non-__rcu pointer old_p.
This commit therefore provides an unrcu_pointer() macro that strips
the __rcu. This macro can be used as follows:
old_p = unrcu_pointer(xchg(&p, RCU_INITIALIZER(new_p)));
Reported-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Stable-dep-of: 5f35a624c1e3 ("drm/nouveau/fence:: fix warning directly dereferencing a rcu pointer")
Signed-off-by: Sasha Levin <sashal@kernel.org>
