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Mon, 27 Jul 2026 13:30:58 -0700 (PDT) From: Allen Pais To: Vinod Koul , Frank Li Cc: Allen Pais , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Kees Cook Subject: [PATCH v2 00/64] dmaengine: migrate channel tasklets to WQ_BH Date: Mon, 27 Jul 2026 13:28:28 -0700 Message-ID: X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260108080332.2341725-1-allen.lkml@gmail.com> References: <20260108080332.2341725-1-allen.lkml@gmail.com> Precedence: bulk X-Mailing-List: dmaengine@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Arnd, Vinod and Frank, This series moves DMAengine client completion bottom halves from private tasklets to a common per-channel API backed by WQ_BH. The first patch introduces the dma_chan_*_bh() API with a tasklet backend and converts virt-dma to it. This separates the driver-facing API from its implementation without changing callback context. The second patch switches that backend to a dedicated WQ_BH | WQ_PERCPU workqueue. WQ_BH keeps callbacks in softirq context, while the common API centralizes initialization, scheduling, and synchronization. The workqueue helpers remain internal to DMAengine, and dma_chan_kill_bh() drains scheduled callbacks to preserve tasklet_kill() semantics. The remaining patches convert driver-owned channel completion tasklets and update virt-dma teardown paths. Tasklets used for controller-level processing, recovery, or other non-client-callback work are deliberately left alone because the appropriate replacement may differ by driver. As agreed in the RFC discussion, selecting hardirq callback delivery is a separate API change and is not part of this series. Earlier discussion: https://lore.kernel.org/all/20260108080332.2341725-1-allen.lkml@gmail.com/ Changes since RFC v1: - split the tasklet-backed channel API from the WQ_BH backend change - keep the low-level workqueue helpers private to DMAengine - preserve tasklet teardown semantics by draining scheduled BH work - convert the remaining driver client-completion tasklets - retain unrelated controller and recovery tasklets - route SF-PDMA terminal errors through virt-dma completion handling - add missing callback synchronization and teardown handling - fix the build failures reported by the kernel test robot - rebase onto the current Linus tree Testing: - x86_64 allmodconfig - make -j$(nproc) W=1 drivers/dma/ - scripts/checkpatch.pl --strict --git origin/master..HEAD - git diff --check origin/master..HEAD Allen Pais (64): dmaengine: add tasklet-backed channel BH helpers dmaengine: back channel BH helpers with WQ_BH dmaengine: apple-admac: use dma_chan BH callback dmaengine: at_xdmac: move irq bottom half to dma_chan BH dmaengine: ep93xx: hook callbacks via dma_chan BH dmaengine: fsldma: migrate tasklet to dma_chan BH dmaengine: fsl_raid: run completions via dma_chan BH dmaengine: imx-dma: flip per-chan tasklet to dma_chan BH dmaengine: ioat: convert cleanup tasklet to dma_chan BH dmaengine: mmp_pdma: replace per-chan tasklet with dma_chan BH dmaengine: mmp_tdma: hook completions to dma_chan BH dmaengine: mv_xor: convert irq tasklet to dma_chan BH dmaengine: mxs-dma: use dma_chan BH scheduling dmaengine: nbpfaxi: switch callbacks to dma_chan BH dmaengine: pch_dma: convert tasklet to dma_chan BH dmaengine: ppc4xx: replace irq tasklet with dma_chan BH dmaengine: ste_dma40: convert per-channel tasklet to dma_chan BH dmaengine: xgene-dma: wire descriptor cleanup to dma_chan BH dmaengine: xilinx-dma: use dma_chan BH instead of tasklets dmaengine: xilinx-dpdma: kill vchan BH on remove dmaengine: zynqmp-dma: switch completion tasklet to dma_chan BH dmaengine: tegra20-apb: use channel BH helpers dmaengine: timb_dma: route callbacks via channel BH dmaengine: txx9dmac: route callbacks via channel BH dmaengine: mv_xor_v2: use channel BH helpers dmaengine: mpc512x: route callbacks via channel BH dmaengine: k3dma: kill vchan BH on remove dmaengine: plx_dma: use channel BH helpers dmaengine: sf-pdma: route error callbacks through channel BH dmaengine: sa11x0-dma: kill vchan BH on remove dmaengine: pl330: route callbacks via channel BH dmaengine: k3-udma: use channel BH for vchan completions dmaengine: sun6i: kill vchan BH on teardown dmaengine: mtk-cqdma: kill vchan BH on teardown dmaengine: altera-msgdma: use channel BH helpers dmaengine: sprd-dma: kill vchan BH on teardown dmaengine: idma64: kill vchan BH on teardown dmaengine: img-mdc-dma: kill vchan BH on teardown dmaengine: fsl-edma-common: kill vchan BH on teardown dmaengine: dw-axi-dmac: kill vchan BH on teardown dmaengine: hsu: kill vchan BH on teardown dmaengine: jz4780: kill vchan BH on teardown dmaengine: pxa_dma: kill vchan BH on teardown dmaengine: mtk-hsdma: kill vchan BH on teardown dmaengine: mtk-uart-apdma: kill vchan BH on teardown dmaengine: imx-sdma: kill vchan BH on teardown dmaengine: loongson1-apb: kill vchan BH on teardown dmaengine: owl-dma: kill vchan BH on teardown dmaengine: hisi: kill vchan BH on teardown dmaengine: dw-edma: kill vchan BH on teardown dmaengine: bcm2835: kill vchan BH on teardown dmaengine: tegra210-adma: kill vchan BH on teardown dmaengine: fsl-qdma: use dma_chan_kill_bh dmaengine: st_fdma: use dma_chan_kill_bh dmaengine: dma-axi-dmac: use dma_chan_kill_bh dmaengine: omap-dma: use dma_chan_kill_bh dmaengine: edma: use dma_chan_kill_bh dmaengine: qcom-adm: use dma_chan_kill_bh dmaengine: tegra186-gpc: use dma_chan_kill_bh dmaengine: bam-dma: use dma_chan_kill_bh dmaengine: dw: defer callbacks via channel BH dmaengine: hidma: defer callbacks via channel BH dmaengine: qcom-gpi: defer callbacks via vchan dmaengine: switchtec: use channel BH helpers drivers/dma/altera-msgdma.c | 14 +-- drivers/dma/apple-admac.c | 16 ++-- drivers/dma/at_xdmac.c | 13 ++- drivers/dma/bcm2835-dma.c | 2 +- drivers/dma/dma-axi-dmac.c | 10 ++- drivers/dma/dma-jz4780.c | 2 +- drivers/dma/dmaengine.c | 89 ++++++++++++++++++- .../dma/dw-axi-dmac/dw-axi-dmac-platform.c | 2 +- drivers/dma/dw-edma/dw-edma-core.c | 2 +- drivers/dma/dw/core.c | 42 +++++++-- drivers/dma/dw/regs.h | 1 + drivers/dma/ep93xx_dma.c | 12 ++- drivers/dma/fsl-edma-common.c | 2 +- drivers/dma/fsl-qdma.c | 2 +- drivers/dma/fsl_raid.c | 11 +-- drivers/dma/fsl_raid.h | 1 - drivers/dma/fsldma.c | 10 +-- drivers/dma/fsldma.h | 1 - drivers/dma/hisi_dma.c | 2 +- drivers/dma/hsu/hsu.c | 2 +- drivers/dma/idma64.c | 4 +- drivers/dma/img-mdc-dma.c | 2 +- drivers/dma/imx-dma.c | 26 +++--- drivers/dma/imx-sdma.c | 4 +- drivers/dma/ioat/dma.c | 14 +-- drivers/dma/ioat/dma.h | 3 +- drivers/dma/ioat/init.c | 2 +- drivers/dma/k3dma.c | 2 +- drivers/dma/loongson/loongson1-apb-dma.c | 2 +- drivers/dma/mediatek/mtk-cqdma.c | 2 +- drivers/dma/mediatek/mtk-hsdma.c | 2 +- drivers/dma/mediatek/mtk-uart-apdma.c | 4 +- drivers/dma/mmp_pdma.c | 13 ++- drivers/dma/mmp_tdma.c | 9 +- drivers/dma/mpc512x_dma.c | 74 +++++++++------ drivers/dma/mv_xor.c | 12 +-- drivers/dma/mv_xor.h | 2 - drivers/dma/mv_xor_v2.c | 20 ++--- drivers/dma/mxs-dma.c | 11 ++- drivers/dma/nbpfaxi.c | 13 ++- drivers/dma/owl-dma.c | 2 +- drivers/dma/pch_dma.c | 14 +-- drivers/dma/pl330.c | 18 ++-- drivers/dma/plx_dma.c | 12 +-- drivers/dma/ppc4xx/adma.c | 14 +-- drivers/dma/ppc4xx/adma.h | 2 - drivers/dma/pxa_dma.c | 2 +- drivers/dma/qcom/bam_dma.c | 4 +- drivers/dma/qcom/gpi.c | 17 +++- drivers/dma/qcom/hidma.c | 18 +++- drivers/dma/qcom/qcom_adm.c | 4 +- drivers/dma/sa11x0-dma.c | 2 +- drivers/dma/sf-pdma/sf-pdma.c | 14 ++- drivers/dma/sprd-dma.c | 2 +- drivers/dma/st_fdma.c | 2 +- drivers/dma/ste_dma40.c | 13 ++- drivers/dma/sun6i-dma.c | 2 +- drivers/dma/switchtec_dma.c | 16 ++-- drivers/dma/tegra186-gpc-dma.c | 2 +- drivers/dma/tegra20-apb-dma.c | 18 ++-- drivers/dma/tegra210-adma.c | 2 +- drivers/dma/ti/edma.c | 2 +- drivers/dma/ti/k3-udma.c | 12 +-- drivers/dma/ti/omap-dma.c | 2 +- drivers/dma/timb_dma.c | 21 +++-- drivers/dma/txx9dmac.c | 12 +-- drivers/dma/txx9dmac.h | 1 - drivers/dma/virt-dma.c | 12 +-- drivers/dma/virt-dma.h | 7 +- drivers/dma/xgene-dma.c | 19 ++-- drivers/dma/xilinx/xilinx_dma.c | 20 ++--- drivers/dma/xilinx/xilinx_dpdma.c | 1 + drivers/dma/xilinx/zynqmp_dma.c | 19 ++-- include/linux/dmaengine.h | 28 ++++++ 74 files changed, 482 insertions(+), 311 deletions(-) base-commit: f5098b6bae761e346ebcd9da7f95622c04733cff -- 2.43.0