On 12/18/2025 9:51 AM, Manivannan Sadhasivam via B4 Relay wrote:
From: Manivannan Sadhasivam <[email protected]>MHI stack offers the 'auto_queue' feature, which allows the MHI stack to auto queue the buffers for the RX path (DL channel). Though this feature simplifies the client driver design, it introduces race between the client drivers and the MHI stack. For instance, with auto_queue, the 'dl_callback' for the DL channel may get called before the client driver is fully probed. This means, by the time the dl_callback gets called, the client driver's structures might not be initialized, leading to NULL ptr dereference. Currently, the drivers have to workaround this issue by initializing the internal structures before calling mhi_prepare_for_transfer_autoqueue(). But even so, there is a chance that the client driver's internal code path may call the MHI queue APIs before mhi_prepare_for_transfer_autoqueue() is called, leading to similar NULL ptr dereference. This issue has been reported on the Qcom X1E80100 CRD machines affecting boot. So to properly fix all these races, drop the MHI 'auto_queue' feature altogether and let the client driver (QRTR) manage the RX buffers manually. In the QRTR driver, queue the RX buffers based on the ring length during probe and recycle the buffers in 'dl_callback' once they are consumed. This also warrants removing the setting of 'auto_queue' flag from controller drivers. Currently, this 'auto_queue' feature is only enabled for IPCR DL channel. So only the QRTR client driver requires the modification. Fixes: 227fee5fc99e ("bus: mhi: core: Add an API for auto queueing buffers for DL channel") Fixes: 68a838b84eff ("net: qrtr: start MHI channel after endpoit creation") Reported-by: Johan Hovold <[email protected]> Closes: https://lore.kernel.org/linux-arm-msm/[email protected] Suggested-by: Chris Lew <[email protected]> Acked-by: Jeff Johnson <[email protected]> # drivers/net/wireless/ath/... Cc: [email protected] Signed-off-by: Manivannan Sadhasivam <[email protected]>
Reviewed-by: Jeff Hugo <[email protected]> For the qaic bits Acked-by: Jeff Hugo <[email protected]>
