| Message ID | 20230608163839.2891748-2-shr@devkernel.io (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | io_uring: add napi busy polling support | expand |
Hi Stefan,
kernel test robot noticed the following build warnings:
[auto build test WARNING on f026be0e1e881e3395c3d5418ffc8c2a2203c3f3]
url: https://github.com/intel-lab-lkp/linux/commits/Stefan-Roesch/net-split-off-__napi_busy_poll-from-napi_busy_poll/20230609-010104
base: f026be0e1e881e3395c3d5418ffc8c2a2203c3f3
patch link: https://lore.kernel.org/r/20230608163839.2891748-2-shr%40devkernel.io
patch subject: [PATCH v15 1/7] net: split off __napi_busy_poll from napi_busy_poll
config: alpha-allyesconfig (https://download.01.org/0day-ci/archive/20230609/202306090341.ShxjwRn1-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 12.3.0
reproduce (this is a W=1 build):
mkdir -p ~/bin
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
git checkout f026be0e1e881e3395c3d5418ffc8c2a2203c3f3
b4 shazam https://lore.kernel.org/r/20230608163839.2891748-2-shr@devkernel.io
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=alpha olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=alpha SHELL=/bin/bash net/core/
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306090341.ShxjwRn1-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> net/core/dev.c:6182:6: warning: no previous prototype for '__napi_busy_loop' [-Wmissing-prototypes]
6182 | void __napi_busy_loop(unsigned int napi_id,
| ^~~~~~~~~~~~~~~~
vim +/__napi_busy_loop +6182 net/core/dev.c
6181
> 6182 void __napi_busy_loop(unsigned int napi_id,
6183 bool (*loop_end)(void *, unsigned long),
6184 void *loop_end_arg, bool prefer_busy_poll, u16 budget,
6185 bool rcu)
6186 {
6187 unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
6188 int (*napi_poll)(struct napi_struct *napi, int budget);
6189 void *have_poll_lock = NULL;
6190 struct napi_struct *napi;
6191
6192 restart:
6193 napi_poll = NULL;
6194
6195 if (!rcu)
6196 rcu_read_lock();
6197
6198 napi = napi_by_id(napi_id);
6199 if (!napi)
6200 goto out;
6201
6202 preempt_disable();
6203 for (;;) {
6204 int work = 0;
6205
6206 local_bh_disable();
6207 if (!napi_poll) {
6208 unsigned long val = READ_ONCE(napi->state);
6209
6210 /* If multiple threads are competing for this napi,
6211 * we avoid dirtying napi->state as much as we can.
6212 */
6213 if (val & (NAPIF_STATE_DISABLE | NAPIF_STATE_SCHED |
6214 NAPIF_STATE_IN_BUSY_POLL)) {
6215 if (prefer_busy_poll)
6216 set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
6217 goto count;
6218 }
6219 if (cmpxchg(&napi->state, val,
6220 val | NAPIF_STATE_IN_BUSY_POLL |
6221 NAPIF_STATE_SCHED) != val) {
6222 if (prefer_busy_poll)
6223 set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
6224 goto count;
6225 }
6226 have_poll_lock = netpoll_poll_lock(napi);
6227 napi_poll = napi->poll;
6228 }
6229 work = napi_poll(napi, budget);
6230 trace_napi_poll(napi, work, budget);
6231 gro_normal_list(napi);
6232 count:
6233 if (work > 0)
6234 __NET_ADD_STATS(dev_net(napi->dev),
6235 LINUX_MIB_BUSYPOLLRXPACKETS, work);
6236 local_bh_enable();
6237
6238 if (!loop_end || loop_end(loop_end_arg, start_time))
6239 break;
6240
6241 if (unlikely(need_resched())) {
6242 if (rcu)
6243 break;
6244 if (napi_poll)
6245 busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
6246 preempt_enable();
6247 rcu_read_unlock();
6248 cond_resched();
6249 if (loop_end(loop_end_arg, start_time))
6250 return;
6251 goto restart;
6252 }
6253 cpu_relax();
6254 }
6255 if (napi_poll)
6256 busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
6257 preempt_enable();
6258 out:
6259 if (!rcu)
6260 rcu_read_unlock();
6261 }
6262
diff --git a/net/core/dev.c b/net/core/dev.c index b3c13e041935..ae90265f4020 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6179,9 +6179,10 @@ 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) +void __napi_busy_loop(unsigned int napi_id, + bool (*loop_end)(void *, unsigned long), + void *loop_end_arg, bool prefer_busy_poll, u16 budget, + bool rcu) { unsigned long start_time = loop_end ? busy_loop_current_time() : 0; int (*napi_poll)(struct napi_struct *napi, int budget); @@ -6191,7 +6192,8 @@ void napi_busy_loop(unsigned int napi_id, restart: napi_poll = NULL; - rcu_read_lock(); + if (!rcu) + rcu_read_lock(); napi = napi_by_id(napi_id); if (!napi) @@ -6237,6 +6239,8 @@ void napi_busy_loop(unsigned int napi_id, break; if (unlikely(need_resched())) { + if (rcu) + break; if (napi_poll) busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget); preempt_enable(); @@ -6252,7 +6256,16 @@ void napi_busy_loop(unsigned int napi_id, busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget); preempt_enable(); out: - rcu_read_unlock(); + if (!rcu) + rcu_read_unlock(); +} + +void napi_busy_loop(unsigned int napi_id, + bool (*loop_end)(void *, unsigned long), + void *loop_end_arg, bool prefer_busy_poll, u16 budget) +{ + __napi_busy_loop(napi_id, loop_end, loop_end_arg, prefer_busy_poll, + budget, false); } EXPORT_SYMBOL(napi_busy_loop);
This splits off the key part of the napi_busy_poll function into its own function __napi_busy_poll. The new function has an additional rcu parameter. This new parameter can be used when the caller is already holding the rcu read lock. 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@devkernel.io> --- net/core/dev.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-)