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Yoshihiro Shimoda authored
commit b2357839 upstream. The old commit 6e4b74e4 ("usb: renesas: fix scheduling in atomic context bug") fixed an atomic issue by using workqueue for the shdmac dmaengine driver. However, this has a potential race condition issue between the work pending and usbhsg_ep_free_request() in gadget mode. When usbhsg_ep_free_request() is called while pending the queue, since the work_struct will be freed and then the work handler is called, kernel panic happens on process_one_work(). To fix the issue, if we could call cancel_work_sync() at somewhere before the free request, it could be easy. However, the usbhsg_ep_free_request() is called on atomic (e.g. f_ncm driver calls free request via gether_disconnect()). For now, almost all users are having "USB-DMAC" and the DMAengine driver can be used on atomic. So, this patch adds a workaround for a race condition to call the DMAengine APIs without the workqueue. This means we still have TODO on shdmac environment (SH7724), but since it doesn't have SMP, the race condition might not happen. Fixes: ab330cf3 ("usb: renesas_usbhs: add support for USB-DMAC") Cc: <stable@vger.kernel.org> # v4.1+ Signed-off-by:
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Signed-off-by:
Felipe Balbi <felipe.balbi@linux.intel.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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