Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'net-prevent-deadlocks-and-mis-configuration-with-per-napi-threaded-config'
Jakub Kicinski says:
====================
net: prevent deadlocks and mis-configuration with per-NAPI threaded config
Running the test added with a recent fix on a driver with persistent
NAPI config leads to a deadlock. The deadlock is fixed by patch 3,
patch 2 is I think a more fundamental problem with the way we
implemented the config.
I hope the fix makes sense, my own thinking is definitely colored
by my preference (IOW how the per-queue config RFC was implemented).
v1: https://lore.kernel.org/20250808014952.724762-1-kuba@kernel.org
====================
Link: https://patch.msgid.link/20250809001205.1147153-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
+27
-8
+4
-1
include/linux/netdevice.h
+4
-1
include/linux/netdevice.h
···
2071
2071
* @max_pacing_offload_horizon: max EDT offload horizon in nsec.
2072
2072
* @napi_config: An array of napi_config structures containing per-NAPI
2073
2073
* settings.
2074
+
* @num_napi_configs: number of allocated NAPI config structs,
2075
+
* always >= max(num_rx_queues, num_tx_queues).
2074
2076
* @gro_flush_timeout: timeout for GRO layer in NAPI
2075
2077
* @napi_defer_hard_irqs: If not zero, provides a counter that would
2076
2078
* allow to avoid NIC hard IRQ, on busy queues.
···
2484
2482
2485
2483
u64 max_pacing_offload_horizon;
2486
2484
struct napi_config *napi_config;
2487
-
unsigned long gro_flush_timeout;
2485
+
u32 num_napi_configs;
2488
2486
u32 napi_defer_hard_irqs;
2487
+
unsigned long gro_flush_timeout;
2489
2488
2490
2489
/**
2491
2490
* @up: copy of @state's IFF_UP, but safe to read with just @lock.
+9
-3
net/core/dev.c
+9
-3
net/core/dev.c
···
6999
6999
enum netdev_napi_threaded threaded)
7000
7000
{
7001
7001
struct napi_struct *napi;
7002
-
int err = 0;
7002
+
int i, err = 0;
7003
7003
7004
7004
netdev_assert_locked_or_invisible(dev);
7005
7005
···
7020
7020
/* The error should not occur as the kthreads are already created. */
7021
7021
list_for_each_entry(napi, &dev->napi_list, dev_list)
7022
7022
WARN_ON_ONCE(napi_set_threaded(napi, threaded));
7023
+
7024
+
/* Override the config for all NAPIs even if currently not listed */
7025
+
for (i = 0; i < dev->num_napi_configs; i++)
7026
+
dev->napi_config[i].threaded = threaded;
7023
7027
7024
7028
return err;
7025
7029
}
···
7357
7353
* Clear dev->threaded if kthread creation failed so that
7358
7354
* threaded mode will not be enabled in napi_enable().
7359
7355
*/
7360
-
if (dev->threaded && napi_kthread_create(napi))
7361
-
dev->threaded = NETDEV_NAPI_THREADED_DISABLED;
7356
+
if (napi_get_threaded_config(dev, napi))
7357
+
if (napi_kthread_create(napi))
7358
+
dev->threaded = NETDEV_NAPI_THREADED_DISABLED;
7362
7359
netif_napi_set_irq_locked(napi, -1);
7363
7360
}
7364
7361
EXPORT_SYMBOL(netif_napi_add_weight_locked);
···
11878
11873
goto free_all;
11879
11874
dev->cfg_pending = dev->cfg;
11880
11875
11876
+
dev->num_napi_configs = maxqs;
11881
11877
napi_config_sz = array_size(maxqs, sizeof(*dev->napi_config));
11882
11878
dev->napi_config = kvzalloc(napi_config_sz, GFP_KERNEL_ACCOUNT);
11883
11879
if (!dev->napi_config)
+8
net/core/dev.h
+8
net/core/dev.h
···
323
323
return NETDEV_NAPI_THREADED_DISABLED;
324
324
}
325
325
326
+
static inline enum netdev_napi_threaded
327
+
napi_get_threaded_config(struct net_device *dev, struct napi_struct *n)
328
+
{
329
+
if (n->config)
330
+
return n->config->threaded;
331
+
return dev->threaded;
332
+
}
333
+
326
334
int napi_set_threaded(struct napi_struct *n,
327
335
enum netdev_napi_threaded threaded);
328
336
+6
-4
tools/testing/selftests/drivers/net/napi_threaded.py
+6
-4
tools/testing/selftests/drivers/net/napi_threaded.py
···
35
35
threaded = cmd(f"cat /sys/class/net/{cfg.ifname}/threaded").stdout
36
36
defer(_set_threaded_state, cfg, threaded)
37
37
38
+
return combined
39
+
38
40
39
41
def enable_dev_threaded_disable_napi_threaded(cfg, nl) -> None:
40
42
"""
···
51
49
napi0_id = napis[0]['id']
52
50
napi1_id = napis[1]['id']
53
51
54
-
_setup_deferred_cleanup(cfg)
52
+
qcnt = _setup_deferred_cleanup(cfg)
55
53
56
54
# set threaded
57
55
_set_threaded_state(cfg, 1)
···
64
62
nl.napi_set({'id': napi1_id, 'threaded': 'disabled'})
65
63
66
64
cmd(f"ethtool -L {cfg.ifname} combined 1")
67
-
cmd(f"ethtool -L {cfg.ifname} combined 2")
65
+
cmd(f"ethtool -L {cfg.ifname} combined {qcnt}")
68
66
_assert_napi_threaded_enabled(nl, napi0_id)
69
67
_assert_napi_threaded_disabled(nl, napi1_id)
70
68
···
82
80
napi0_id = napis[0]['id']
83
81
napi1_id = napis[1]['id']
84
82
85
-
_setup_deferred_cleanup(cfg)
83
+
qcnt = _setup_deferred_cleanup(cfg)
86
84
87
85
# set threaded
88
86
_set_threaded_state(cfg, 1)
···
92
90
_assert_napi_threaded_enabled(nl, napi1_id)
93
91
94
92
cmd(f"ethtool -L {cfg.ifname} combined 1")
95
-
cmd(f"ethtool -L {cfg.ifname} combined 2")
93
+
cmd(f"ethtool -L {cfg.ifname} combined {qcnt}")
96
94
97
95
# check napi threaded is set for both napis
98
96
_assert_napi_threaded_enabled(nl, napi0_id)