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Date:   Tue, 22 Oct 2019 12:28:39 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     kbuild@lists.01.org, Suwan Kim <suwan.kim027@gmail.com>
Cc:     kbuild-all@lists.01.org, linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: drivers/usb/usbip/stub_rx.c:505 stub_recv_cmd_submit() error:
 uninitialized symbol 'nents'.
Message-ID: <20191022092839.GD10833@kadam>
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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   7d194c2100ad2a6dded545887d02754948ca5241
commit: ea44d190764b4422af4d1c29eaeb9e69e353b406 usbip: Implement SG support to vhci-hcd and stub driver
date:   7 weeks ago

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

New smatch warnings:
drivers/usb/usbip/stub_rx.c:505 stub_recv_cmd_submit() error: uninitialized symbol 'nents'.

Old smatch warnings:
drivers/usb/usbip/stub_rx.c:450 stub_recv_xbuff() error: uninitialized symbol 'ret'.

# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ea44d190764b4422af4d1c29eaeb9e69e353b406
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git remote update linus
git checkout ea44d190764b4422af4d1c29eaeb9e69e353b406
vim +/nents +505 drivers/usb/usbip/stub_rx.c

4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  453  static void stub_recv_cmd_submit(struct stub_device *sdev,
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  454  				 struct usbip_header *pdu)
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  455  {
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  456  	struct stub_priv *priv;
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  457  	struct usbip_device *ud = &sdev->ud;
2d8f4595d1f275 drivers/staging/usbip/stub_rx.c Max Vozeler        2011-01-12  458  	struct usb_device *udev = sdev->udev;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  459  	struct scatterlist *sgl = NULL, *sg;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  460  	void *buffer = NULL;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  461  	unsigned long long buf_len;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  462  	int nents;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  463  	int num_urbs = 1;
c6688ef9f29762 drivers/usb/usbip/stub_rx.c     Shuah Khan         2017-12-07  464  	int pipe = get_pipe(sdev, pdu);
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  465  	int use_sg = pdu->u.cmd_submit.transfer_flags & URB_DMA_MAP_SG;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  466  	int support_sg = 1;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  467  	int np = 0;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  468  	int ret, i;
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  469  
635f545a7e8be7 drivers/usb/usbip/stub_rx.c     Shuah Khan         2017-12-07  470  	if (pipe == -1)
635f545a7e8be7 drivers/usb/usbip/stub_rx.c     Shuah Khan         2017-12-07  471  		return;
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  472  
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  473  	priv = stub_priv_alloc(sdev, pdu);
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  474  	if (!priv)
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  475  		return;
4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09  476  
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  477  	buf_len = (unsigned long long)pdu->u.cmd_submit.transfer_buffer_length;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  478  
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  479  	/* allocate urb transfer buffer, if needed */
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  480  	if (buf_len) {
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  481  		if (use_sg) {
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  482  			sgl = sgl_alloc(buf_len, GFP_KERNEL, &nents);
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  483  			if (!sgl)
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  484  				goto err_malloc;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  485  		} else {
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  486  			buffer = kzalloc(buf_len, GFP_KERNEL);
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  487  			if (!buffer)
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  488  				goto err_malloc;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  489  		}
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  490  	}
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  491  
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  492  	/* Check if the server's HCD supports SG */
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  493  	if (use_sg && !udev->bus->sg_tablesize) {

Smatch thinks "use_sg" can be true when "buf_len" is zero.  It's hard
to tell if Smatch is right or wrong without more context...

ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  494  		/*
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  495  		 * If the server's HCD doesn't support SG, break a single SG
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  496  		 * request into several URBs and map each SG list entry to
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  497  		 * corresponding URB buffer. The previously allocated SG
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  498  		 * list is stored in priv->sgl (If the server's HCD support SG,
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  499  		 * SG list is stored only in urb->sg) and it is used as an
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  500  		 * indicator that the server split single SG request into
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  501  		 * several URBs. Later, priv->sgl is used by stub_complete() and
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  502  		 * stub_send_ret_submit() to reassemble the divied URBs.
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  503  		 */
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  504  		support_sg = 0;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28 @505  		num_urbs = nents;
                                                                                                ^^^^^^^^^^^^^^^^

ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  506  		priv->completed_urbs = 0;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  507  		pdu->u.cmd_submit.transfer_flags &= ~URB_DMA_MAP_SG;
ea44d190764b44 drivers/usb/usbip/stub_rx.c     Suwan Kim          2019-08-28  508  	}

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