drivers/vfio/pci/vfio_pci_rdwr.c:169 vfio_pci_bar_rw() warn: always true condition '(done >= 0) => (0-u32max >= 0)'

Hi Alex,

FYI, there are new smatch warnings show up in

tree: git://github.com/awilliam/linux-vfio.git vfio-vga

head:   2c2e21fa66c40ed7b8e434c86a9f2ab0c879f21d
commit: f4d38f216ef420595d12f74b256b3961eb4c3c14 [3/5] vfio-pci: Cleanup BAR access

New smatch warnings:
drivers/vfio/pci/vfio_pci_rdwr.c:169 vfio_pci_bar_rw() warn: always true condition '(done >= 0) => (0-u32max >= 0)'

vim +169 drivers/vfio/pci/vfio_pci_rdwr.c

f4d38f21 Alex Williamson 2013-01-16  153  		if (!io) {
f4d38f21 Alex Williamson 2013-01-16  154  			pci_release_selected_regions(pdev, 1 << bar);
f4d38f21 Alex Williamson 2013-01-16  155  			return -ENOMEM;
89e1f7d4 Alex Williamson 2012-07-31  156  		}
89e1f7d4 Alex Williamson 2012-07-31  157  
f4d38f21 Alex Williamson 2013-01-16  158  		vdev->barmap[bar] = io;
f4d38f21 Alex Williamson 2013-01-16  159  	} else
89e1f7d4 Alex Williamson 2012-07-31  160  		io = vdev->barmap[bar];
89e1f7d4 Alex Williamson 2012-07-31  161  
f4d38f21 Alex Williamson 2013-01-16  162  	if (bar == vdev->msix_bar) {
f4d38f21 Alex Williamson 2013-01-16  163  		x_start = vdev->msix_offset;
f4d38f21 Alex Williamson 2013-01-16  164  		x_end = vdev->msix_offset + vdev->msix_size;
89e1f7d4 Alex Williamson 2012-07-31  165  	}
89e1f7d4 Alex Williamson 2012-07-31  166  
f4d38f21 Alex Williamson 2013-01-16  167  	done = do_io_rw(io, buf, pos, count, x_start, x_end, iswrite);
89e1f7d4 Alex Williamson 2012-07-31  168  
f4d38f21 Alex Williamson 2013-01-16 @169  	if (done >= 0)
f4d38f21 Alex Williamson 2013-01-16  170  		*ppos += done;
89e1f7d4 Alex Williamson 2012-07-31  171  
89e1f7d4 Alex Williamson 2012-07-31  172  	if (bar == PCI_ROM_RESOURCE)
89e1f7d4 Alex Williamson 2012-07-31  173  		pci_unmap_rom(pdev, io);
89e1f7d4 Alex Williamson 2012-07-31  174  
f4d38f21 Alex Williamson 2013-01-16  175  	return done;
89e1f7d4 Alex Williamson 2012-07-31  176  }

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Quoted 5 lines · Fengguang Wu

Hi Alex,

FYI, there are new smatch warnings show up in

tree: git://github.com/awilliam/linux-vfio.git vfio-vga

Thanks for the bug report. I never would have expected but reports from an unadvertised branch but it's a really cool service. Thanks for providing it!