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net: add napi_busy_loop_rcu() 

This adds the napi_busy_loop_rcu() function. This function assumes that
the calling function is already holding the rcu read lock and
napi_busy_loop() does not need to take the rcu read lock. Add a
NAPI_F_NO_SCHED flag, which tells __napi_busy_loop() to abort if we
need to reschedule rather than drop the RCU read lock and reschedule.

Signed-off-by: Stefan Roesch <shr@devkernel.io>
Link: https://lore.kernel.org/r/20230608163839.2891748-3-shr@devkernel.io
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Stefan Roesch 2024-02-06 09:30:04 -07:00 committed by Jakub Kicinski
parent 13d381b440
commit b4e8ae5c8c
2 changed files with 19 additions and 0 deletions
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4
include/net/busy_poll.h
View File

@ -48,6 +48,10 @@ void napi_busy_loop(unsigned int napi_id,
bool (*loop_end)(void *, unsigned long),
void *loop_end_arg, bool prefer_busy_poll, u16 budget);
void napi_busy_loop_rcu(unsigned int napi_id,
bool (*loop_end)(void *, unsigned long),
void *loop_end_arg, bool prefer_busy_poll, u16 budget);
#else /* CONFIG_NET_RX_BUSY_POLL */
static inline unsigned long net_busy_loop_on(void)
{

15
net/core/dev.c
View File

@ -6179,6 +6179,7 @@ static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule)
enum {
NAPI_F_PREFER_BUSY_POLL = 1,
NAPI_F_END_ON_RESCHED = 2,
};
static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock,
@ -6285,6 +6286,8 @@ count:
break;
if (unlikely(need_resched())) {
if (flags & NAPI_F_END_ON_RESCHED)
break;
if (napi_poll)
busy_poll_stop(napi, have_poll_lock, flags, budget);
if (!IS_ENABLED(CONFIG_PREEMPT_RT))
@ -6304,6 +6307,18 @@ count:
preempt_enable();
}
void napi_busy_loop_rcu(unsigned int napi_id,
bool (*loop_end)(void *, unsigned long),
void *loop_end_arg, bool prefer_busy_poll, u16 budget)
{
unsigned flags = NAPI_F_END_ON_RESCHED;
if (prefer_busy_poll)
flags |= NAPI_F_PREFER_BUSY_POLL;
__napi_busy_loop(napi_id, loop_end, loop_end_arg, flags, budget);
}
void napi_busy_loop(unsigned int napi_id,
bool (*loop_end)(void *, unsigned long),
void *loop_end_arg, bool prefer_busy_poll, u16 budget)