Re: [PATCH v3] ath10k: Fix crash during rmmod when probe firmware fails
From: Valo, Kalle <hidden>
Date: 2017-01-25 13:29:47
Mohammed Shafi Shajakhan [off-list ref] writes:
From: Mohammed Shafi Shajakhan <redacted>
This fixes the below crash when ath10k probe firmware fails,
NAPI polling tries to access a rx ring resource which was never
allocated, fix this by disabling NAPI right away once the probe
firmware fails by calling 'ath10k_hif_stop'. Its good to note
that the error is never propogated to 'ath10k_pci_probe' when
ath10k_core_register fails, so calling 'ath10k_hif_stop' to cleanup
PCI related things seems to be ok
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: __ath10k_htt_rx_ring_fill_n+0x19/0x230 [ath10k_core]
__ath10k_htt_rx_ring_fill_n+0x19/0x230 [ath10k_core]
Call Trace:
[<ffffffffa113ec62>] ath10k_htt_rx_msdu_buff_replenish+0x42/0x90
[ath10k_core]
[<ffffffffa113f393>] ath10k_htt_txrx_compl_task+0x433/0x17d0
[ath10k_core]
[<ffffffff8114406d>] ? __wake_up_common+0x4d/0x80
[<ffffffff811349ec>] ? cpu_load_update+0xdc/0x150
[<ffffffffa119301d>] ? ath10k_pci_read32+0xd/0x10 [ath10k_pci]
[<ffffffffa1195b17>] ath10k_pci_napi_poll+0x47/0x110 [ath10k_pci]
[<ffffffff817863af>] net_rx_action+0x20f/0x370
Reported-by: Ben Greear <redacted>
Fixes: 3c97f5de1f28 ("ath10k: implement NAPI support")
Signed-off-by: Mohammed Shafi Shajakhan <redacted>Is there an easy way to reproduce this bug? I don't see it on my x86 laptop with qca988x and I call rmmod all the time. I would like to test this myself.
quoted hunk ↗ jump to hunk
--- a/drivers/net/wireless/ath/ath10k/core.c +++ b/drivers/net/wireless/ath/ath10k/core.c@@ -2164,6 +2164,7 @@ static int ath10k_core_probe_fw(struct ath10k *ar) ath10k_core_free_firmware_files(ar);=20 err_power_down: + ath10k_hif_stop(ar); ath10k_hif_power_down(ar); =20 return ret;
This breaks the symmetry, we should not be calling ath10k_hif_stop() if we haven't called ath10k_hif_start() from the same function. This can just create a bigger mess later, for example with other bus support like sdio or usb. In theory it should enough that we call ath10k_hif_power_down() and pci.c does the rest correctly "behind the scenes". I investigated this a bit and I think the real cause is that we call napi_enable() from ath10k_pci_hif_power_up() and napi_disable() from ath10k_pci_hif_stop(). Does anyone remember why? I was expecting that we would call napi_enable()/napi_disable() either in ath10k_hif_power_up/down() or ath10k_hif_start()/stop(), but not mixed like it's currently. --=20 Kalle Valo=