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Message-ID: <20240206163422.646218-2-axboe@kernel.dk>
Date: Tue, 6 Feb 2024 09:30:03 -0700
From: Jens Axboe <axboe@...nel.dk>
To: io-uring@...r.kernel.org,
netdev@...r.kernel.org
Cc: kuba@...nel.org,
olivier@...llion01.com,
Stefan Roesch <shr@...kernel.io>,
Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 1/7] net: split off __napi_busy_poll from napi_busy_poll
From: Stefan Roesch <shr@...kernel.io>
This splits off the key part of the napi_busy_poll function into its own
function, __napi_busy_poll, and changes the prefer_busy_poll bool to be
flag based to allow passing in more flags in the future.
This is done in preparation for an additional napi_busy_poll() function,
that doesn't take the rcu_read_lock(). The new function is introduced
in the next patch.
Signed-off-by: Stefan Roesch <shr@...kernel.io>
Link: https://lore.kernel.org/r/20230608163839.2891748-2-shr@devkernel.io
Signed-off-by: Jens Axboe <axboe@...nel.dk>
---
net/core/dev.c | 42 ++++++++++++++++++++++++++++--------------
1 file changed, 28 insertions(+), 14 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index cb2dab0feee0..1eaed657f2c2 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6177,8 +6177,12 @@ static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule)
clear_bit(NAPI_STATE_SCHED, &napi->state);
}
-static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool prefer_busy_poll,
- u16 budget)
+enum {
+ NAPI_F_PREFER_BUSY_POLL = 1,
+};
+
+static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock,
+ unsigned flags, u16 budget)
{
bool skip_schedule = false;
unsigned long timeout;
@@ -6198,7 +6202,7 @@ static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool
local_bh_disable();
- if (prefer_busy_poll) {
+ if (flags & NAPI_F_PREFER_BUSY_POLL) {
napi->defer_hard_irqs_count = READ_ONCE(napi->dev->napi_defer_hard_irqs);
timeout = READ_ONCE(napi->dev->gro_flush_timeout);
if (napi->defer_hard_irqs_count && timeout) {
@@ -6222,23 +6226,23 @@ static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool
local_bh_enable();
}
-void napi_busy_loop(unsigned int napi_id,
- bool (*loop_end)(void *, unsigned long),
- void *loop_end_arg, bool prefer_busy_poll, u16 budget)
+static void __napi_busy_loop(unsigned int napi_id,
+ bool (*loop_end)(void *, unsigned long),
+ void *loop_end_arg, unsigned flags, u16 budget)
{
unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
int (*napi_poll)(struct napi_struct *napi, int budget);
void *have_poll_lock = NULL;
struct napi_struct *napi;
+ WARN_ON_ONCE(!rcu_read_lock_held());
+
restart:
napi_poll = NULL;
- rcu_read_lock();
-
napi = napi_by_id(napi_id);
if (!napi)
- goto out;
+ return;
if (!IS_ENABLED(CONFIG_PREEMPT_RT))
preempt_disable();
@@ -6254,14 +6258,14 @@ void napi_busy_loop(unsigned int napi_id,
*/
if (val & (NAPIF_STATE_DISABLE | NAPIF_STATE_SCHED |
NAPIF_STATE_IN_BUSY_POLL)) {
- if (prefer_busy_poll)
+ if (flags & NAPI_F_PREFER_BUSY_POLL)
set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
goto count;
}
if (cmpxchg(&napi->state, val,
val | NAPIF_STATE_IN_BUSY_POLL |
NAPIF_STATE_SCHED) != val) {
- if (prefer_busy_poll)
+ if (flags & NAPI_F_PREFER_BUSY_POLL)
set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
goto count;
}
@@ -6282,11 +6286,12 @@ void napi_busy_loop(unsigned int napi_id,
if (unlikely(need_resched())) {
if (napi_poll)
- busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
+ busy_poll_stop(napi, have_poll_lock, flags, budget);
if (!IS_ENABLED(CONFIG_PREEMPT_RT))
preempt_enable();
rcu_read_unlock();
cond_resched();
+ rcu_read_lock();
if (loop_end(loop_end_arg, start_time))
return;
goto restart;
@@ -6294,10 +6299,19 @@ void napi_busy_loop(unsigned int napi_id,
cpu_relax();
}
if (napi_poll)
- busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
+ busy_poll_stop(napi, have_poll_lock, flags, budget);
if (!IS_ENABLED(CONFIG_PREEMPT_RT))
preempt_enable();
-out:
+}
+
+void napi_busy_loop(unsigned int napi_id,
+ bool (*loop_end)(void *, unsigned long),
+ void *loop_end_arg, bool prefer_busy_poll, u16 budget)
+{
+ unsigned flags = prefer_busy_poll ? NAPI_F_PREFER_BUSY_POLL : 0;
+
+ rcu_read_lock();
+ __napi_busy_loop(napi_id, loop_end, loop_end_arg, flags, budget);
rcu_read_unlock();
}
EXPORT_SYMBOL(napi_busy_loop);
--
2.43.0
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