net: qrtr: start MHI channel after endpoit creation

MHI channel may generates event/interrupt right after enabling.
It may leads to 2 race conditions issues.

1)
Such event may be dropped by qcom_mhi_qrtr_dl_callback() at check:

if (!qdev || mhi_res->transaction_status)
return;

Because dev_set_drvdata(&mhi_dev->dev, qdev) may be not performed at
this moment. In this situation qrtr-ns will be unable to enumerate
services in device.
---------------------------------------------------------------

2)
Such event may come at the moment after dev_set_drvdata() and
before qrtr_endpoint_register(). In this case kernel will panic with
accessing wrong pointer at qcom_mhi_qrtr_dl_callback():

rc = qrtr_endpoint_post(&qdev->ep, mhi_res->buf_addr,
mhi_res->bytes_xferd);

Because endpoint is not created yet.
--------------------------------------------------------------
So move mhi_prepare_for_transfer_autoqueue after endpoint creation
to fix it.

Fixes: a2e2cc0dbb11 ("net: qrtr: Start MHI channels during init")
Signed-off-by: Maxim Kochetkov <fido_max@inbox.ru>
Reviewed-by: Hemant Kumar <quic_hemantk@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

bus: mhi: core: Add an API for auto queueing buffers for DL channel

Add a new API "mhi_prepare_for_transfer_autoqueue" for using with client
drivers like QRTR to request MHI core to autoqueue buffers for the DL
channel along with starting both UL and DL channels.

So far, the "auto_queue" flag specified by the controller drivers in
channel definition served this purpose but this will be removed at some
point in future.

Cc: netdev@vger.kernel.org
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Co-developed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20211216081227.237749-9-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Revert "bus: mhi: Add inbound buffers allocation flag"

This reverts commit 0092a1e3f7636ff4e202a41b0320690699247e22

This should be reverted in the char-misc-next branch to make merging
with Linus's branch possible due to issues with the mhi code that was
found in the networking tree.

Link: https://lore.kernel.org/r/20210827175852.GB15018@thinkpad
Reported-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bhaumik Bhatt <bbhatt@codeaurora.org>
Cc: Hemant Kumar <hemantk@codeaurora.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: Loic Poulain <loic.poulain@linaro.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

bus: mhi: Add inbound buffers allocation flag

Currently, the MHI controller driver defines which channels should
have their inbound buffers allocated and queued. But ideally, this is
something that should be decided by the MHI device driver instead,
which actually deals with that buffers.

Add a flag parameter to mhi_prepare_for_transfer allowing to specify
if buffers have to be allocated and queued by the MHI stack.

Keep auto_queue flag for now, but should be removed at some point.

Link: https://lore.kernel.org/r/1624566520-20406-1-git-send-email-loic.poulain@linaro.org
Tested-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20210802051255.5771-2-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Revert "net: really fix the build..."

This reverts commit ce78ffa3ef1681065ba451cfd545da6126f5ca88.

Wren and Nicolas reported that ath11k was failing to initialise QCA6390
Wi-Fi 6 device with error:

qcom_mhi_qrtr: probe of mhi0_IPCR failed with error -22

Commit ce78ffa3ef16 ("net: really fix the build..."), introduced in
v5.14-rc5, caused this regression in qrtr. Most likely all ath11k
devices are broken, but I only tested QCA6390. Let's revert the broken
commit so that ath11k works again.

Reported-by: Wren Turkal <wt@penguintechs.org>
Reported-by: Nicolas Schichan <nschichan@freebox.fr>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210826172816.24478-1-kvalo@codeaurora.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: really fix the build...

Signed-off-by: David S. Miller <davem@davemloft.net>

net: qrtr: Avoid potential use after free in MHI send

It is possible that the MHI ul_callback will be invoked immediately
following the queueing of the skb for transmission, leading to the
callback decrementing the refcount of the associated sk and freeing the
skb.

As such the dereference of skb and the increment of the sk refcount must
happen before the skb is queued, to avoid the skb to be used after free
and potentially the sk to drop its last refcount..

Fixes: 6e728f321393 ("net: qrtr: Add MHI transport layer")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: qrtr: Unprepare MHI channels during remove

Reset MHI device channels when driver remove is called due to
module unload or any crash scenario. This will make sure that
MHI channels no longer remain enabled for transfers since the
MHI stack does not take care of this anymore after the auto-start
channels feature was removed.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

net: qrtr: Start MHI channels during init

Start MHI device channels so that transfers can be performed.
The MHI stack does not auto-start channels anymore.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

net: qrtr: Add MHI transport layer

MHI is the transport layer used for communicating to the external modems.
Hence, this commit adds MHI transport layer support to QRTR for
transferring the QMI messages over IPC Router.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>