linux-kernel - Re: [PATCH v3] usb: xhci: tegra: fix sleep in atomic call

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Message-ID: <1a7bd64b-7d4e-61fc-797c-816a2fe8d83e@nvidia.com>
Date:   Tue, 21 Mar 2023 07:15:54 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Haotien Hsu <haotienh@...dia.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-usb@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     JC Kuo <jckuo@...dia.com>, Wayne Chang <waynec@...dia.com>
Subject: Re: [PATCH v3] usb: xhci: tegra: fix sleep in atomic call


On 21/03/2023 07:13, Haotien Hsu wrote:
> From: Wayne Chang <waynec@...dia.com>
> 
> When we set the OTG port to Host mode, we observed the following splat:
> [  167.057718] BUG: sleeping function called from invalid context at
> include/linux/sched/mm.h:229
> [  167.057872] Workqueue: events tegra_xusb_usb_phy_work
> [  167.057954] Call trace:
> [  167.057962]  dump_backtrace+0x0/0x210
> [  167.057996]  show_stack+0x30/0x50
> [  167.058020]  dump_stack_lvl+0x64/0x84
> [  167.058065]  dump_stack+0x14/0x34
> [  167.058100]  __might_resched+0x144/0x180
> [  167.058140]  __might_sleep+0x64/0xd0
> [  167.058171]  slab_pre_alloc_hook.constprop.0+0xa8/0x110
> [  167.058202]  __kmalloc_track_caller+0x74/0x2b0
> [  167.058233]  kvasprintf+0xa4/0x190
> [  167.058261]  kasprintf+0x58/0x90
> [  167.058285]  tegra_xusb_find_port_node.isra.0+0x58/0xd0
> [  167.058334]  tegra_xusb_find_port+0x38/0xa0
> [  167.058380]  tegra_xusb_padctl_get_usb3_companion+0x38/0xd0
> [  167.058430]  tegra_xhci_id_notify+0x8c/0x1e0
> [  167.058473]  notifier_call_chain+0x88/0x100
> [  167.058506]  atomic_notifier_call_chain+0x44/0x70
> [  167.058537]  tegra_xusb_usb_phy_work+0x60/0xd0
> [  167.058581]  process_one_work+0x1dc/0x4c0
> [  167.058618]  worker_thread+0x54/0x410
> [  167.058650]  kthread+0x188/0x1b0
> [  167.058672]  ret_from_fork+0x10/0x20
> 
> The function tegra_xusb_padctl_get_usb3_companion eventually calls
> tegra_xusb_find_port and this in turn calls kasprintf which might sleep
> and so cannot be called from an atomic context.
> 
> Fix this by moving the call to tegra_xusb_padctl_get_usb3_companion to
> the tegra_xhci_id_work function where it is really needed.
> 
> Fixes: f836e7843036 ("usb: xhci-tegra: Add OTG support")
> Cc: stable@...r.kernel.org
> Signed-off-by: Wayne Chang <waynec@...dia.com>
> Signed-off-by: Haotien Hsu <haotienh@...dia.com>
> ---
> V2 -> V3: Add version information
> V1 -> V2: Add "Fixes" and "Cc:" lines and update copyright years
> ---
> 
>   drivers/usb/host/xhci-tegra.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> index 1ff22f675930..8dbce2cdb7e4 100644
> --- a/drivers/usb/host/xhci-tegra.c
> +++ b/drivers/usb/host/xhci-tegra.c
> @@ -2,7 +2,7 @@
>   /*
>    * NVIDIA Tegra xHCI host controller driver
>    *
> - * Copyright (c) 2014-2020, NVIDIA CORPORATION. All rights reserved.
> + * Copyright (c) 2014-2020,2023, NVIDIA CORPORATION. All rights reserved.

Please drop this from this patch. Greg indicated in V1, that this should 
not be part of this patch.

Jon

-- 
nvpublic