usb: gadget: f_fs: set req->num_sgs as 0 for non-sg transfer
The UDC core uses req->num_sgs to judge if scatter buffer list is used. Eg: usb_gadget_map_request_by_dev. For f_fs sync io mode, the request is re-used for each request, so if the 1st request->length > PAGE_SIZE, and the 2nd request->length is <= PAGE_SIZE, the f_fs uses the 1st req->num_sgs for the 2nd request, it causes the UDC core get the wrong req->num_sgs value (The 2nd request doesn't use sg). For f_fs async io mode, it is not harm to initialize req->num_sgs as 0 either, in case, the UDC driver doesn't zeroed request structure. Cc: Jun Li <jun.li@nxp.com> Cc: stable <stable@vger.kernel.org> Fixes: 772a7a72 ("usb: gadget: f_fs: Allow scatter-gather buffers") Signed-off-by: NPeter Chen <peter.chen@nxp.com> Signed-off-by: NFelipe Balbi <balbi@kernel.org> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
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