Re: [PATCH v2 net-next] devlink: Add missed notifications iterators

[Keller, Jacob E]

On 9/29/2021 7:18 AM, Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@xxxxxxxxxx>
> 
> The commit mentioned in Fixes line missed a couple of notifications that
> were registered before devlink_register() and should be delayed too.
> 
> As such, the too early placed WARN_ON() check spotted it.
> 

I was just about to report this for devlink regions!

> WARNING: CPU: 1 PID: 6540 at net/core/devlink.c:5158 devlink_nl_region_notify+0x184/0x1e0 net/core/devlink.c:5158
> Modules linked in:
> CPU: 1 PID: 6540 Comm: syz-executor.0 Not tainted 5.15.0-rc2-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:devlink_nl_region_notify+0x184/0x1e0 net/core/devlink.c:5158
> Code: 38 41 b8 c0 0c 00 00 31 d2 48 89 ee 4c 89 e7 e8 72 1a 26 00 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e e9 01 bd 41 fa
> e8 fc bc 41 fa <0f> 0b e9 f7 fe ff ff e8 f0 bc 41 fa 0f 0b eb da 4c 89 e7 e8 c4 18
> RSP: 0018:ffffc90002d6f658 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: ffff88801f08d580 RSI: ffffffff87344e94 RDI: 0000000000000003
> RBP: ffff88801ee42100 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffffff87344d8a R11: 0000000000000000 R12: ffff88801c1dc000
> R13: 0000000000000000 R14: 000000000000002c R15: ffff88801c1dc070
> FS:  0000555555e8e400(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055dd7c590310 CR3: 0000000069a09000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  devlink_region_create+0x39f/0x4c0 net/core/devlink.c:10327
>  nsim_dev_dummy_region_init drivers/net/netdevsim/dev.c:481 [inline]
>  nsim_dev_probe+0x5f6/0x1150 drivers/net/netdevsim/dev.c:1479
>  call_driver_probe drivers/base/dd.c:517 [inline]
>  really_probe+0x245/0xcc0 drivers/base/dd.c:596
>  __driver_probe_device+0x338/0x4d0 drivers/base/dd.c:751
>  driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:781
>  __device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:898
>  bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427
>  __device_attach+0x228/0x4a0 drivers/base/dd.c:969
>  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487
>  device_add+0xc35/0x21b0 drivers/base/core.c:3359
>  nsim_bus_dev_new drivers/net/netdevsim/bus.c:435 [inline]
>  new_device_store+0x48b/0x770 drivers/net/netdevsim/bus.c:302
>  bus_attr_store+0x72/0xa0 drivers/base/bus.c:122
>  sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139
>  kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
>  call_write_iter include/linux/fs.h:2163 [inline]
>  new_sync_write+0x429/0x660 fs/read_write.c:507
>  vfs_write+0x7cf/0xae0 fs/read_write.c:594
>  ksys_write+0x12d/0x250 fs/read_write.c:647
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f328409d3ef
> Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 99 fd ff ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01
> 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 cc fd ff ff 48
> RSP: 002b:00007ffdc6851140 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f328409d3ef
> RDX: 0000000000000003 RSI: 00007ffdc6851190 RDI: 0000000000000004
> RBP: 0000000000000004 R08: 0000000000000000 R09: 00007ffdc68510e0
> R10: 0000000000000000 R11: 0000000000000293 R12: 00007f3284144971
> R13: 00007ffdc6851190 R14: 0000000000000000 R15: 00007ffdc6851860
> 
> Fixes: 474053c980a0 ("devlink: Notify users when objects are accessible")
> Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Tested-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
> Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>

I ran into this earlier today and this looks like how I was going to
suggest fixing it.

Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>

> ---
>  net/core/devlink.c | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/devlink.c b/net/core/devlink.c
> index 06edb2f1d21e..b64303085d0e 100644
> --- a/net/core/devlink.c
> +++ b/net/core/devlink.c
> @@ -1072,7 +1072,9 @@ static void devlink_rate_notify(struct devlink_rate *devlink_rate,
>  	int err;
>  
>  	WARN_ON(cmd != DEVLINK_CMD_RATE_NEW && cmd != DEVLINK_CMD_RATE_DEL);
> -	WARN_ON(!xa_get_mark(&devlinks, devlink->index, DEVLINK_REGISTERED));
> +
> +	if (!xa_get_mark(&devlinks, devlink->index, DEVLINK_REGISTERED))
> +		return;
>  
>  	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
>  	if (!msg)
> @@ -5155,7 +5157,8 @@ static void devlink_nl_region_notify(struct devlink_region *region,
>  	struct sk_buff *msg;
>  
>  	WARN_ON(cmd != DEVLINK_CMD_REGION_NEW && cmd != DEVLINK_CMD_REGION_DEL);
> -	WARN_ON(!xa_get_mark(&devlinks, devlink->index, DEVLINK_REGISTERED));
> +	if (!xa_get_mark(&devlinks, devlink->index, DEVLINK_REGISTERED))
> +		return;
>  
>  	msg = devlink_nl_region_notify_build(region, snapshot, cmd, 0, 0);
>  	if (IS_ERR(msg))
> @@ -8981,6 +8984,8 @@ static void devlink_notify_register(struct devlink *devlink)
>  	struct devlink_trap_group_item *group_item;
>  	struct devlink_trap_item *trap_item;
>  	struct devlink_port *devlink_port;
> +	struct devlink_rate *rate_node;
> +	struct devlink_region *region;
>  
>  	devlink_notify(devlink, DEVLINK_CMD_NEW);
>  	list_for_each_entry(devlink_port, &devlink->port_list, list)
> @@ -8997,6 +9002,12 @@ static void devlink_notify_register(struct devlink *devlink)
>  	list_for_each_entry(trap_item, &devlink->trap_list, list)
>  		devlink_trap_notify(devlink, trap_item, DEVLINK_CMD_TRAP_NEW);
>  
> +	list_for_each_entry(rate_node, &devlink->rate_list, list)
> +		devlink_rate_notify(rate_node, DEVLINK_CMD_RATE_NEW);
> +
> +	list_for_each_entry(region, &devlink->region_list, list)
> +		devlink_nl_region_notify(region, NULL, DEVLINK_CMD_REGION_NEW);
> +
>  	devlink_params_publish(devlink);
>  }
>  
> @@ -9006,9 +9017,17 @@ static void devlink_notify_unregister(struct devlink *devlink)
>  	struct devlink_trap_group_item *group_item;
>  	struct devlink_trap_item *trap_item;
>  	struct devlink_port *devlink_port;
> +	struct devlink_rate *rate_node;
> +	struct devlink_region *region;
>  
>  	devlink_params_unpublish(devlink);
>  
> +	list_for_each_entry_reverse(region, &devlink->region_list, list)
> +		devlink_nl_region_notify(region, NULL, DEVLINK_CMD_REGION_DEL);
> +
> +	list_for_each_entry_reverse(rate_node, &devlink->rate_list, list)
> +		devlink_rate_notify(rate_node, DEVLINK_CMD_RATE_DEL);
> +
>  	list_for_each_entry_reverse(trap_item, &devlink->trap_list, list)
>  		devlink_trap_notify(devlink, trap_item, DEVLINK_CMD_TRAP_DEL);
>  
>