[PATCH 5.4 008/158] lan743x: fix issue causing intermittent kernel log warnings

Greg Kroah-Hartman
2020-11-23T12:35:01Z

From: Sven Van Asbroeck <thesven73@gmail.com>

[ Upstream commit e35df62e04cc6fc4b9d90d054732f138349ff9b1 ]

When running this chip on arm imx6, we intermittently observe
the following kernel warning in the log, especially when the
system is under high load:

[ 50.119484] ------------[ cut here ]------------
[ 50.124377] WARNING: CPU: 0 PID: 303 at kernel/softirq.c:169 __local_bh_enable_ip+0x100/0x184
[ 50.132925] IRQs not enabled as expected
[ 50.159250] CPU: 0 PID: 303 Comm: rngd Not tainted 5.7.8 #1
[ 50.164837] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 50.171395] [<c0111a38>] (unwind_backtrace) from [<c010be28>] (show_stack+0x10/0x14)
[ 50.179162] [<c010be28>] (show_stack) from [<c05b9dec>] (dump_stack+0xac/0xd8)
[ 50.186408] [<c05b9dec>] (dump_stack) from [<c0122e40>] (__warn+0xd0/0x10c)
[ 50.193391] [<c0122e40>] (__warn) from [<c0123238>] (warn_slowpath_fmt+0x98/0xc4)
[ 50.200892] [<c0123238>] (warn_slowpath_fmt) from [<c012b010>] (__local_bh_enable_ip+0x100/0x184)
[ 50.209860] [<c012b010>] (__local_bh_enable_ip) from [<bf09ecbc>] (destroy_conntrack+0x48/0xd8 [nf_conntrack])
[ 50.220038] [<bf09ecbc>] (destroy_conntrack [nf_conntrack]) from [<c0ac9b58>] (nf_conntrack_destroy+0x94/0x168)
[ 50.230160] [<c0ac9b58>] (nf_conntrack_destroy) from [<c0a4aaa0>] (skb_release_head_state+0xa0/0xd0)
[ 50.239314] [<c0a4aaa0>] (skb_release_head_state) from [<c0a4aadc>] (skb_release_all+0xc/0x24)
[ 50.247946] [<c0a4aadc>] (skb_release_all) from [<c0a4b4cc>] (consume_skb+0x74/0x17c)
[ 50.255796] [<c0a4b4cc>] (consume_skb) from [<c081a2dc>] (lan743x_tx_release_desc+0x120/0x124)
[ 50.264428] [<c081a2dc>] (lan743x_tx_release_desc) from [<c081a98c>] (lan743x_tx_napi_poll+0x5c/0x18c)
[ 50.273755] [<c081a98c>] (lan743x_tx_napi_poll) from [<c0a6b050>] (net_rx_action+0x118/0x4a4)
[ 50.282306] [<c0a6b050>] (net_rx_action) from [<c0101364>] (__do_softirq+0x13c/0x53c)
[ 50.290157] [<c0101364>] (__do_softirq) from [<c012b29c>] (irq_exit+0x150/0x17c)
[ 50.297575] [<c012b29c>] (irq_exit) from [<c0196a08>] (__handle_domain_irq+0x60/0xb0)
[ 50.305423] [<c0196a08>] (__handle_domain_irq) from [<c05d44fc>] (gic_handle_irq+0x4c/0x90)
[ 50.313790] [<c05d44fc>] (gic_handle_irq) from [<c0100ed4>] (__irq_usr+0x54/0x80)
[ 50.321287] Exception stack(0xecd99fb0 to 0xecd99ff8)
[ 50.326355] 9fa0: 1cf1aa74 00000001 00000001 00000000
[ 50.334547] 9fc0: 00000001 00000000 00000000 00000000 00000000 00000000 00004097 b6d17d14
[ 50.342738] 9fe0: 00000001 b6d17c60 00000000 b6e71f94 800b0010 ffffffff
[ 50.349364] irq event stamp: 2525027
[ 50.352955] hardirqs last enabled at (2525026): [<c0a6afec>] net_rx_action+0xb4/0x4a4
[ 50.360892] hardirqs last disabled at (2525027): [<c0d6d2fc>] _raw_spin_lock_irqsave+0x1c/0x50
[ 50.369517] softirqs last enabled at (2524660): [<c01015b4>] __do_softirq+0x38c/0x53c
[ 50.377446] softirqs last disabled at (2524693): [<c012b29c>] irq_exit+0x150/0x17c
[ 50.385027] ---[ end trace c0b571db4bc8087d ]---

The driver is calling dev_kfree_skb() from code inside a spinlock,
where h/w interrupts are disabled. This is forbidden, as documented
in include/linux/netdevice.h. The correct function to use
dev_kfree_skb_irq(), or dev_kfree_skb_any().

Fix by using the correct dev_kfree_skb_xxx() functions:

in lan743x_tx_release_desc():
called by lan743x_tx_release_completed_descriptors()
called by in lan743x_tx_napi_poll()
which holds a spinlock
called by lan743x_tx_release_all_descriptors()
called by lan743x_tx_close()
which can-sleep
conclusion: use dev_kfree_skb_any()

in lan743x_tx_xmit_frame():
which holds a spinlock
conclusion: use dev_kfree_skb_irq()

in lan743x_tx_close():
which can-sleep
conclusion: use dev_kfree_skb()

in lan743x_rx_release_ring_element():
called by lan743x_rx_close()
which can-sleep
called by lan743x_rx_open()
which can-sleep
conclusion: use dev_kfree_skb()

Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver")
Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
Link: https://lore.kernel.org/r/20201112185949.11315-1-TheSven73@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/microchip/lan743x_main.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1242,13 +1242,13 @@ clean_up_data_descriptor:
goto clear_active;

if (!(buffer_info->flags & TX_BUFFER_INFO_FLAG_TIMESTAMP_REQUESTED)) {
- dev_kfree_skb(buffer_info->skb);
+ dev_kfree_skb_any(buffer_info->skb);
goto clear_skb;
}

if (cleanup) {
lan743x_ptp_unrequest_tx_timestamp(tx->adapter);
- dev_kfree_skb(buffer_info->skb);
+ dev_kfree_skb_any(buffer_info->skb);
} else {
ignore_sync = (buffer_info->flags &
TX_BUFFER_INFO_FLAG_IGNORE_SYNC) != 0;
@@ -1558,7 +1558,7 @@ static netdev_tx_t lan743x_tx_xmit_frame
if (required_number_of_descriptors >
lan743x_tx_get_avail_desc(tx)) {
if (required_number_of_descriptors > (tx->ring_size - 1)) {
- dev_kfree_skb(skb);
+ dev_kfree_skb_irq(skb);
} else {
/* save to overflow buffer */
tx->overflow_skb = skb;
@@ -1591,7 +1591,7 @@ static netdev_tx_t lan743x_tx_xmit_frame
start_frame_length,
do_timestamp,
skb->ip_summed == CHECKSUM_PARTIAL)) {
- dev_kfree_skb(skb);
+ dev_kfree_skb_irq(skb);
goto unlock;
}

@@ -1610,7 +1610,7 @@ static netdev_tx_t lan743x_tx_xmit_frame
* frame assembler clean up was performed inside
* lan743x_tx_frame_add_fragment
*/
- dev_kfree_skb(skb);
+ dev_kfree_skb_irq(skb);
goto unlock;
}
}