Hi Andreas,

On Fri, 2015-07-31 at 11:16 +0200, Andreas Schwab wrote:

Daniel Axtens [off-list ref] writes:

quoted

Every time I build cxl I see the following warnings:

/scratch/dja/linux-capi/drivers/misc/cxl/pci.c: In function ‘sanitise_afu_regs’:
/scratch/dja/linux-capi/drivers/misc/cxl/pci.c:712:6: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses]
   if (reg & CXL_PSL_DSISR_TRANS)
      ^
/scratch/dja/linux-capi/drivers/misc/cxl/irq.c: In function ‘fail_psl_irq’:
/scratch/dja/linux-capi/drivers/misc/cxl/irq.c:184:5: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses]
  if (irq_info->dsisr & CXL_PSL_DSISR_TRANS)
     ^

Why are they ambigous?  Why doesn't cxl_p2n_write(afu, CXL_PSL_TFC_An,
CXL_PSL_TFC_An_AE) expand to a proper statement?

#define cxl_p2n_write(afu, reg, val) \
	out_be64(_cxl_p2n_addr(afu, reg), val)

I realised that I started seeing this when I was working on my EEH
patches, which change the definition to:

#define cxl_p2n_write(afu, reg, val) \
	if (cxl_adapter_link_ok(afu->adapter)) \
		out_be64(_cxl_p2n_addr(afu, reg), val)


I'll redo the patch to change the write functions to wrap the if
statement so they cease to be ambiguous. I'll also spin a patch to
enable -Werror so I catch this earlier next time.

Thanks for the feedback, it was very helpful in me figuring out the root
cause.

-- 
Regards,
Daniel