[PATCH v2 6/8] nvmet: pci-epf: Use dmaengine_prep_config_single_safe() API

Frank Li
2025-12-18T15:57:18Z

Use the new dmaengine_prep_config_single_safe() API to combine the
configuration and descriptor preparation into a single call.

Since dmaengine_prep_config_single_safe() performs the configuration and
preparation atomically and dw edma driver implement prep_config_sg() call
back, so dmaengine_prep_config_single() is reentriable, the mutex can be
removed.

Tested-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
drivers/nvme/target/pci-epf.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/drivers/nvme/target/pci-epf.c b/drivers/nvme/target/pci-epf.c
index 56b1c6a7706a9e2dd9d8aaf17b440129b948486c..8b5ea5d4c79dfd461b767cfd4033a9e4604c94b1 100644
--- a/drivers/nvme/target/pci-epf.c
+++ b/drivers/nvme/target/pci-epf.c
@@ -388,22 +388,15 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf,
return -EINVAL;
}

- mutex_lock(lock);
-
dma_dev = dmaengine_get_dma_device(chan);
dma_addr = dma_map_single(dma_dev, seg->buf, seg->length, dir);
ret = dma_mapping_error(dma_dev, dma_addr);
if (ret)
- goto unlock;
-
- ret = dmaengine_slave_config(chan, &sconf);
- if (ret) {
- dev_err(dev, "Failed to configure DMA channel\n");
- goto unmap;
- }
+ return ret;

- desc = dmaengine_prep_slave_single(chan, dma_addr, seg->length,
- sconf.direction, DMA_CTRL_ACK);
+ desc = dmaengine_prep_config_single_safe(chan, dma_addr, seg->length,
+ sconf.direction,
+ DMA_CTRL_ACK, &sconf);
if (!desc) {
dev_err(dev, "Failed to prepare DMA\n");
ret = -EIO;
@@ -426,9 +419,6 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf,
unmap:
dma_unmap_single(dma_dev, dma_addr, seg->length, dir);

-unlock:
- mutex_unlock(lock);
-
return ret;
}

--
2.34.1