| Message ID | 20210715164544.6827-1-logang@deltatee.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | .map_sg() error cleanup | expand |
On Thu, Jul 15, 2021 at 10:45:28AM -0600, Logan Gunthorpe wrote: > Hi, > > This series is spun out and expanded from my work to add P2PDMA support > to DMA map operations[1]. > > The P2PDMA work requires distinguishing different error conditions in > a map_sg operation. dma_map_sgtable() already allows for returning an > error code (where as dma_map_sg() is only allowed to return zero) > however, it currently only returns -EINVAL when a .map_sg() call returns > zero. > > This series cleans up all .map_sg() implementations to return appropriate > error codes. After the cleanup, dma_map_sg() will still return zero, > however dma_map_sgtable() will pass the error code from the .map_sg() > call. Thanks go to Martn Oliveira for doing a lot of the cleanup of the > obscure implementations. > > The patch set is based off of v5.14-rc1 and a git repo can be found > here: Have all the callers for dma_map_sg() been updated to check for error codes? If not, isn't that a pre-requisit to this patch set? From what I see in Linus' current tree, we still have cases today where the return value of dma_map_sg() is compared with zero to detect failure, so I think that needs fixing before we start changing the dma_map_sg() implementation to return negative numbers. I also notice that there are various places that don't check the return value - and returning a negative number instead of zero may well cause random other bits to be set in fields. So, I think there's a fair amount of work to do in all the drivers before this change can be considered.
On 2021-07-15 10:53 a.m., Russell King (Oracle) wrote: > On Thu, Jul 15, 2021 at 10:45:28AM -0600, Logan Gunthorpe wrote: >> Hi, >> >> This series is spun out and expanded from my work to add P2PDMA support >> to DMA map operations[1]. >> >> The P2PDMA work requires distinguishing different error conditions in >> a map_sg operation. dma_map_sgtable() already allows for returning an >> error code (where as dma_map_sg() is only allowed to return zero) >> however, it currently only returns -EINVAL when a .map_sg() call returns >> zero. >> >> This series cleans up all .map_sg() implementations to return appropriate >> error codes. After the cleanup, dma_map_sg() will still return zero, >> however dma_map_sgtable() will pass the error code from the .map_sg() >> call. Thanks go to Martn Oliveira for doing a lot of the cleanup of the >> obscure implementations. >> >> The patch set is based off of v5.14-rc1 and a git repo can be found >> here: > > Have all the callers for dma_map_sg() been updated to check for error > codes? If not, isn't that a pre-requisit to this patch set? No. Perhaps I wasn't clear enough: This series is changing only impelemntations of .map_sg(). It does *not* change the return code of dma_map_sg(). dma_map_sg() will continue to return zero on error for the foreseeable future. The dma_map_sgtable() call already allows returning error codes and it will pass the new error code through. This is what will be used in the P2PDMA work. Logan