[PATCH v4] usb: mtu3: fix panic in mtu3_gadget_stop()

[Chunfeng Yun]

On Thu, 2020-08-27 at 22:42 +0800, Macpaul Lin wrote:
> This patch fixes a possible issue when mtu3_gadget_stop()
> already assigned NULL to mtu->gadget_driver during mtu_gadget_disconnect().
> 
> [<ffffff9008161974>] notifier_call_chain+0xa4/0x128
> [<ffffff9008161fd4>] __atomic_notifier_call_chain+0x84/0x138
> [<ffffff9008162ec0>] notify_die+0xb0/0x120
> [<ffffff900809e340>] die+0x1f8/0x5d0
> [<ffffff90080d03b4>] __do_kernel_fault+0x19c/0x280
> [<ffffff90080d04dc>] do_bad_area+0x44/0x140
> [<ffffff90080d0f9c>] do_translation_fault+0x4c/0x90
> [<ffffff9008080a78>] do_mem_abort+0xb8/0x258
> [<ffffff90080849d0>] el1_da+0x24/0x3c
> [<ffffff9009bde01c>] mtu3_gadget_disconnect+0xac/0x128
> [<ffffff9009bd576c>] mtu3_irq+0x34c/0xc18
> [<ffffff90082ac03c>] __handle_irq_event_percpu+0x2ac/0xcd0
> [<ffffff90082acae0>] handle_irq_event_percpu+0x80/0x138
> [<ffffff90082acc44>] handle_irq_event+0xac/0x148
> [<ffffff90082b71cc>] handle_fasteoi_irq+0x234/0x568
> [<ffffff90082a8708>] generic_handle_irq+0x48/0x68
> [<ffffff90082a96ac>] __handle_domain_irq+0x264/0x1740
> [<ffffff90080819f4>] gic_handle_irq+0x14c/0x250
> [<ffffff9008084cec>] el1_irq+0xec/0x194
> [<ffffff90085b985c>] dma_pool_alloc+0x6e4/0xae0
> [<ffffff9008d7f890>] cmdq_mbox_pool_alloc_impl+0xb0/0x238
> [<ffffff9008d80904>] cmdq_pkt_alloc_buf+0x2dc/0x7c0
> [<ffffff9008d80f60>] cmdq_pkt_add_cmd_buffer+0x178/0x270
> [<ffffff9008d82320>] cmdq_pkt_perf_begin+0x108/0x148
> [<ffffff9008d824d8>] cmdq_pkt_create+0x178/0x1f0
> [<ffffff9008f96230>] mtk_crtc_config_default_path+0x328/0x7a0
> [<ffffff90090246cc>] mtk_drm_idlemgr_kick+0xa6c/0x1460
> [<ffffff9008f9bbb4>] mtk_drm_crtc_atomic_begin+0x1a4/0x1a68
> [<ffffff9008e8df9c>] drm_atomic_helper_commit_planes+0x154/0x878
> [<ffffff9008f2fb70>] mtk_atomic_complete.isra.16+0xe80/0x19c8
> [<ffffff9008f30910>] mtk_atomic_commit+0x258/0x898
> [<ffffff9008ef142c>] drm_atomic_commit+0xcc/0x108
> [<ffffff9008ef7cf0>] drm_mode_atomic_ioctl+0x1c20/0x2580
> [<ffffff9008ebc768>] drm_ioctl_kernel+0x118/0x1b0
> [<ffffff9008ebcde8>] drm_ioctl+0x5c0/0x920
> [<ffffff900863b030>] do_vfs_ioctl+0x188/0x1820
> [<ffffff900863c754>] SyS_ioctl+0x8c/0xa0
> 
> Fixes: df2069acb005 ("usb: Add MediaTek USB3 DRD driver")
> Signed-off-by: Macpaul Lin <macpaul.lin at mediatek.com>
> Cc: stable at vger.kernel.org
> ---
> Changes for v4:
>   - Add a "Fixes:" line.  Thanks Felipe.
> Changes for v3:
>   - Call synchronize_irq() in mtu3_gadget_stop() instead of remembering
>     callback function in mtu3_gadget_disconnect().
>     Thanks for Alan's suggestion.
> Changes for v2:
>   - Check mtu_gadget_driver out of spin_lock might still not work.
>     We use a temporary pointer to remember the callback function.
> 
>  drivers/usb/mtu3/mtu3_gadget.c |    1 +
>  1 file changed, 1 insertions(+)
> 
> diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c
> index 1de5c9a..1ab3d3a 100644
> --- a/drivers/usb/mtu3/mtu3_gadget.c
> +++ b/drivers/usb/mtu3/mtu3_gadget.c
> @@ -564,6 +564,7 @@ static int mtu3_gadget_stop(struct usb_gadget *g)
>  
>  	spin_unlock_irqrestore(&mtu->lock, flags);
>  
> +	synchronize_irq(mtu->irq);
>  	return 0;
>  }
>  
Acked-by: Chunfeng Yun <chunfeng.yun at mediatek.com>

Thanks a lot