Re: [PATCH 2/2] scsi: Use new __dma_buffer to align sense buffer in scsi_cmnd

 > It's also incomplete as a fix because I don't see what guarantees the
 > buffer size will always exceed cache line size

There's a macro trick that adds a pad member after the buffer too, so
that it gets rounded up to the cacheline size:

 > +#define __dma_aligned	  	__attribute__((aligned(ARCH_MIN_DMA_ALIGNMENT)))
 > +#define __dma_buffer		__dma_buffer_line(__LINE__)
 > +#define __dma_buffer_line(line)	__dma_aligned;\
 > +				char __dma_pad_##line[0] __dma_aligned

So that part is OK at least.

 - R.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

---

• References:
  • [PATCH 2/2] scsi: Use new __dma_buffer to align sense buffer in scsi_cmnd
    • From: Benjamin Herrenschmidt <[email protected]>
  • Re: [PATCH 2/2] scsi: Use new __dma_buffer to align sense buffer in scsi_cmnd
    • From: Alan Cox <[email protected]>

• Prev by Date: Re: Major regression on hackbench with SLUB (more numbers)
• Next by Date: Re: [PATCH 1/2] DMA buffer alignment annotations
• Previous by thread: Re: [PATCH 2/2] scsi: Use new __dma_buffer to align sense buffer in scsi_cmnd
• Next by thread: Re: [PATCH 2/2] scsi: Use new __dma_buffer to align sense buffer in scsi_cmnd
• Index(es):
  • Date
  • Thread

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]