Re: DMA-API backtrace from rtsx_usb_ms driver

[Roger Tseng <rogerable@realtek.com>]

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On Thu, 2015-02-19 at 11:58 -0500, Josh Boyer wrote:
> Hi All,
> 
> We've had a few bug reports with the stack trace below.  It looks like
> the ms_read_bytes and ms_write_bytes functions in
> drivers/memstick/host/rtsx_usb_mc.c are using a stack variable when
> calling rtsx_usb_ep0_read_register.  That eventually gets to the
> DMA-API debugging checks, which throws the warning backtrace.
> 
> A typical fix is to replace:
> 
>                 u8 val;
> 
>                 rtsx_usb_ep0_read_register(ucr, MS_TRANS_CFG, &val);
>                 dev_dbg(ms_dev(host), "MS_TRANS_CFG: 0x%02x\n", val);
> 
> with something like:
> 
>                 u8 val = kzalloc(sizeof(u8), GFP_KERNEL);
>                 if (!val) return -ENOMEM;
> 
>                 rtsx_usb_ep0_read_register(ucr, MS_TRANS_CFG, &val);
>                 dev_dbg(ms_dev(host), "MS_TRANS_CFG: 0x%02x\n", val);
> 
>                 <....>
>                 kfree(val);
> 
> However, I'm not familiar enough with this driver to know if this
> function is called frequently in an IRQ handler, etc.  If the above
> pseudo code looks sufficient, I can come up with a patch.
> 
Thanks for reporting this.

rtsx_usb_ep0_read_register() is not called in any interrupt context. It 
is a high-priority(control pipe) but less used alternative to
communicate with device. It is primarily for error handling.

I'll fix it inside rtsx_usb_ep0_read_register() itself by a DMA'able
double buffer because it could be called somewhere else(e.g. mmc side).

> WARNING: CPU: 1 PID: 25 at lib/dma-debug.c:1166 check_for_stack+0x96/0xe0()
> ehci-pci 0000:00:1a.0: DMA-API: device driver maps memory from stack
> [addr=ffff8801199e3cef]
> Modules linked in: rtsx_usb_ms arc4 memstick intel_rapl iosf_mbi
> rtl8192ce snd_hda_codec_hdmi snd_hda_codec_realtek
> snd_hda_codec_generic snd_hda_intel rtl_pci rtl8192c_common
> snd_hda_controller x86_pkg_temp_thermal snd_hda_codec rtlwifi mac80211
> coretemp kvm_intel kvm iTCO_wdt snd_hwdep snd_seq snd_seq_device
> crct10dif_pclmul iTCO_vendor_support sparse_keymap cfg80211
> crc32_pclmul snd_pcm crc32c_intel ghash_clmulni_intel rfkill i2c_i801
> snd_timer shpchp snd serio_raw mei_me lpc_ich soundcore mei tpm_tis
> tpm wmi nfsd auth_rpcgss nfs_acl lockd grace sunrpc i915
> rtsx_usb_sdmmc mmc_core 8021q uas garp stp i2c_algo_bit llc mrp
> drm_kms_helper usb_storage drm rtsx_usb mfd_core r8169 mii video
> CPU: 1 PID: 25 Comm: kworker/1:2 Not tainted 3.20.0-0.rc0.git7.3.fc22.x86_64 #1
> Hardware name: WB WB-B06211/WB-B0621, BIOS EB062IWB V1.0 12/12/2013
> Workqueue: events rtsx_usb_ms_handle_req [rtsx_usb_ms]
>  0000000000000000 000000003d188e66 ffff8801199e3808 ffffffff8187642b
>  0000000000000000 ffff8801199e3860 ffff8801199e3848 ffffffff810ab39a
>  ffff8801199e3864 ffff8801199e3cef ffff880119b57098 ffff880119b37320
> Call Trace:
>  [<ffffffff8187642b>] dump_stack+0x4c/0x65
>  [<ffffffff810ab39a>] warn_slowpath_common+0x8a/0xc0
>  [<ffffffff810ab425>] warn_slowpath_fmt+0x55/0x70
>  [<ffffffff8187efe6>] ? _raw_spin_unlock_irqrestore+0x36/0x70
>  [<ffffffff81453156>] check_for_stack+0x96/0xe0
>  [<ffffffff81453934>] debug_dma_map_page+0x104/0x150
>  [<ffffffff81613b86>] usb_hcd_map_urb_for_dma+0x646/0x790
>  [<ffffffff81614165>] usb_hcd_submit_urb+0x1d5/0xa90
>  [<ffffffff81106f8f>] ? mark_held_locks+0x7f/0xc0
>  [<ffffffff81106f8f>] ? mark_held_locks+0x7f/0xc0
>  [<ffffffff81103a15>] ? lockdep_init_map+0x65/0x5d0
>  [<ffffffff81615d7e>] usb_submit_urb+0x42e/0x5f0
>  [<ffffffff81616787>] usb_start_wait_urb+0x77/0x190
>  [<ffffffff8124f035>] ? __kmalloc+0x205/0x2d0
>  [<ffffffff8161697c>] usb_control_msg+0xdc/0x130
>  [<ffffffffa0031669>] rtsx_usb_ep0_read_register+0x59/0x70 [rtsx_usb]
>  [<ffffffffa00310c1>] ? rtsx_usb_get_rsp+0x41/0x50 [rtsx_usb]
>  [<ffffffffa071da4e>] rtsx_usb_ms_handle_req+0x7ce/0x9c5 [rtsx_usb_ms]
>  [<ffffffff810cc60b>] ? process_one_work+0x19b/0x860
>  [<ffffffff810cc6a2>] process_one_work+0x232/0x860
>  [<ffffffff810cc60b>] ? process_one_work+0x19b/0x860
>  [<ffffffff810ccdaa>] ? worker_thread+0xda/0x470
>  [<ffffffff810ccd23>] worker_thread+0x53/0x470
>  [<ffffffff810cccd0>] ? process_one_work+0x860/0x860
>  [<ffffffff810d31b4>] kthread+0x104/0x120
>  [<ffffffff810e7fb5>] ? local_clock+0x25/0x30
>  [<ffffffff810d30b0>] ? kthread_create_on_node+0x250/0x250
>  [<ffffffff8187fb7c>] ret_from_fork+0x7c/0xb0
>  [<ffffffff810d30b0>] ? kthread_create_on_node+0x250/0x250
> 
> josh
> 
> ------Please consider the environment before printing this e-mail.

-- 
Best regards,
Roger Tseng


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