Commit 157ae5ffd7 dmaengine: mediatek: Fix a possible deadlock error
in mtk_cqdma_tx_status() fixed locks but kept unused varibale leading to
warning and build failure (due to warning treated as errors)
drivers/dma/mediatek/mtk-cqdma.c: In function 'mtk_cqdma_find_active_desc':
drivers/dma/mediatek/mtk-cqdma.c:423:23: error: unused variable 'flags' [-Werror=unused-variable]
423 | unsigned long flags;
| ^~~~~
Fix by dropping this unused flag
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 157ae5ffd7 ("dmaengine: mediatek: Fix a possible deadlock error in mtk_cqdma_tx_status()")
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Fix a potential deadlock bug. Observe that in the mtk-cqdma.c
file, functions like mtk_cqdma_issue_pending() and
mtk_cqdma_free_active_desc() properly acquire the pc lock before the vc
lock when handling pc and vc fields. However, mtk_cqdma_tx_status()
violates this order by first acquiring the vc lock before invoking
mtk_cqdma_find_active_desc(), which subsequently takes the pc lock. This
reversed locking sequence (vc → pc) contradicts the established
pc → vc order and creates deadlock risks.
Fix the issue by moving the vc lock acquisition code from
mtk_cqdma_find_active_desc() to mtk_cqdma_tx_status(). Ensure the pc lock
is acquired before the vc lock in the calling function to maintain correct
locking hierarchy. Note that since mtk_cqdma_find_active_desc() is a
static function with only one caller (mtk_cqdma_tx_status()), this
modification safely eliminates the deadlock possibility without affecting
other components.
This possible bug is found by an experimental static analysis tool
developed by our team. This tool analyzes the locking APIs to extract
function pairs that can be concurrently executed, and then analyzes the
instructions in the paired functions to identify possible concurrency bugs
including deadlocks, data races and atomicity violations.
Fixes: b1f01e48df ("dmaengine: mediatek: Add MediaTek Command-Queue DMA controller for MT6765 SoC")
Cc: stable@vger.kernel.org
Signed-off-by: Qiu-ji Chen <chenqiuji666@gmail.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250508073634.3719-1-chenqiuji666@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
After commit 0edb555a65 ("platform: Make platform_driver::remove()
return void") .remove() is (again) the right callback to implement for
platform drivers.
Convert all platform drivers below drivers/dma after the previous
conversion commits apart from the wireless drivers to use .remove(),
with the eventual goal to drop struct platform_driver::remove_new(). As
.remove() and .remove_new() have the same prototypes, conversion is done
by just changing the structure member name in the driver initializer.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20241004062227.187726-2-u.kleine-koenig@baylibre.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new() which already returns void. Eventually after all drivers
are converted, .remove_new() is renamed to .remove().
Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230919133207.1400430-23-u.kleine-koenig@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230718143138.1066177-1-robh@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
allocation of IRQ resources in DT core code, this causes an issue
when using hierarchical interrupt domains using "interrupts" property
in the node as this bypasses the hierarchical setup and messes up the
irq chaining.
In preparation for removal of static setup of IRQ resource from DT core
code use platform_get_irq().
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220404155557.27316-4-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
In preparation for unconditionally passing the
struct tasklet_struct pointer to all tasklet
callbacks, switch to using the new tasklet_setup()
and from_tasklet() to pass the tasklet pointer explicitly.
Signed-off-by: Romain Perier <romain.perier@gmail.com>
Signed-off-by: Allen Pais <allen.lkml@gmail.com>
Link: https://lore.kernel.org/r/20200831103542.305571-14-allen.lkml@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Simplify this function implementation a bit by using
a known wrapper function.
This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Link: https://lore.kernel.org/r/c7e3bbae-44fa-9019-18ee-c6cdfd7c2a14@web.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The mtk_cqdma_poll_engine_done() function takes a true/false parameter
where true means it's called from atomic context. There are a couple
places where it was set to false but it's actually in atomic context
so it should be true.
All the callers for mtk_cqdma_hard_reset() are holding a spin_lock and
in mtk_cqdma_free_chan_resources() we take a spin_lock before calling
the mtk_cqdma_poll_engine_done() function.
Fixes: b1f01e48df ("dmaengine: mediatek: Add MediaTek Command-Queue DMA controller for MT6765 SoC")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
MediaTek Command-Queue DMA controller (CQDMA) on MT6765 SoC is dedicated
to memory-to-memory transfer through queue based descriptor management.
There are only 3 physical channels inside CQDMA, while the driver is
extended to support 32 virtual channels for multiple dma users to issue
dma requests onto the CQDMA simultaneously.
Signed-off-by: Shun-Chih Yu <shun-chih.yu@mediatek.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
