linux-kernel - Re: [PATCH v2] i3c: Use i3cdev->desc->info instead of calling i3c_device_get

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Message-ID: <72410501-657b-40ec-b959-a736c913c486@ijzerbout.nl>
Date: Tue, 19 Nov 2024 21:51:39 +0100
From: Kees Bakker <kees@...erbout.nl>
To: mtk25126 <defa.li@...iatek.com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 wsd_upstream@...iatek.com, mingchang.jia@...iatek.com,
 yuhan.wei@...iatek.com, hao.lin@...iatek.com
Subject: Re: [PATCH v2] i3c: Use i3cdev->desc->info instead of calling
 i3c_device_get_info() to avoid deadlock

Op 07-11-2024 om 14:25 schreef mtk25126:
> From: Defa Li <defa.li@...iatek.com>
>
> A deadlock may happen since the i3c_master_register() acquires
> &i3cbus->lock twice. See the log below.
> Use i3cdev->desc->info instead of calling i3c_device_info() to
> avoid acquiring the lock twice.
>
> v2:
>    - Modified the title and commit message
>
> ============================================
> WARNING: possible recursive locking detected
> 6.11.0-mainline
> --------------------------------------------
> init/1 is trying to acquire lock:
> f1ffff80a6a40dc0 (&i3cbus->lock){++++}-{3:3}, at: i3c_bus_normaluse_lock
>
> but task is already holding lock:
> f1ffff80a6a40dc0 (&i3cbus->lock){++++}-{3:3}, at: i3c_master_register
>
> other info that might help us debug this:
>   Possible unsafe locking scenario:
>
>         CPU0
>         ----
>    lock(&i3cbus->lock);
>    lock(&i3cbus->lock);
>
>   *** DEADLOCK ***
>
>   May be due to missing lock nesting notation
>
> 2 locks held by init/1:
>   #0: fcffff809b6798f8 (&dev->mutex){....}-{3:3}, at: __driver_attach
>   #1: f1ffff80a6a40dc0 (&i3cbus->lock){++++}-{3:3}, at: i3c_master_register
>
> stack backtrace:
> CPU: 6 UID: 0 PID: 1 Comm: init
> Call trace:
>   dump_backtrace+0xfc/0x17c
>   show_stack+0x18/0x28
>   dump_stack_lvl+0x40/0xc0
>   dump_stack+0x18/0x24
>   print_deadlock_bug+0x388/0x390
>   __lock_acquire+0x18bc/0x32ec
>   lock_acquire+0x134/0x2b0
>   down_read+0x50/0x19c
>   i3c_bus_normaluse_lock+0x14/0x24
>   i3c_device_get_info+0x24/0x58
>   i3c_device_uevent+0x34/0xa4
>   dev_uevent+0x310/0x384
>   kobject_uevent_env+0x244/0x414
>   kobject_uevent+0x14/0x20
>   device_add+0x278/0x460
>   device_register+0x20/0x34
>   i3c_master_register_new_i3c_devs+0x78/0x154
>   i3c_master_register+0x6a0/0x6d4
>   mtk_i3c_master_probe+0x3b8/0x4d8
>   platform_probe+0xa0/0xe0
>   really_probe+0x114/0x454
>   __driver_probe_device+0xa0/0x15c
>   driver_probe_device+0x3c/0x1ac
>   __driver_attach+0xc4/0x1f0
>   bus_for_each_dev+0x104/0x160
>   driver_attach+0x24/0x34
>   bus_add_driver+0x14c/0x294
>   driver_register+0x68/0x104
>   __platform_driver_register+0x20/0x30
>   init_module+0x20/0xfe4
>   do_one_initcall+0x184/0x464
>   do_init_module+0x58/0x1ec
>   load_module+0xefc/0x10c8
>   __arm64_sys_finit_module+0x238/0x33c
>   invoke_syscall+0x58/0x10c
>   el0_svc_common+0xa8/0xdc
>   do_el0_svc+0x1c/0x28
>   el0_svc+0x50/0xac
>   el0t_64_sync_handler+0x70/0xbc
>   el0t_64_sync+0x1a8/0x1ac
>
> Signed-off-by: Defa Li <defa.li@...iatek.com>
> ---
>   drivers/i3c/master.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 6f3eb710a75d..bb8a8bf0c4c7 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -282,7 +282,8 @@ static int i3c_device_uevent(const struct device *dev, struct kobj_uevent_env *e
>   	struct i3c_device_info devinfo;
>   	u16 manuf, part, ext;
>   
> -	i3c_device_get_info(i3cdev, &devinfo);
> +	if (i3cdev->desc)
> +		devinfo = i3cdev->desc->info;
Now you have left devinfo unitialized if i3cdev->desc == NULL
You have to figure out what to do in that case.
>   	manuf = I3C_PID_MANUF_ID(devinfo.pid);
>   	part = I3C_PID_PART_ID(devinfo.pid);
>   	ext = I3C_PID_EXTRA_INFO(devinfo.pid);