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[v2,kvmtool,3/7] pci: Fix pci_dev_* print macros

Message ID 20211012132510.42134-4-alexandru.elisei@arm.com (mailing list archive)
State New, archived
Headers show
Series vfio/pci: Fix MSIX table and PBA size allocation | expand

Commit Message

Alexandru Elisei Oct. 12, 2021, 1:25 p.m. UTC 
Evaluate the "pci_hdr" argument before attempting to deference a field.
This fixes cryptic errors like this one, which came about during a
debugging session:

vfio/pci.c: In function 'vfio_pci_bar_activate':
include/kvm/pci.h:18:40: error: invalid type argument of '->' (have 'struct pci_device_header')
  pr_warning("[%04x:%04x] " fmt, pci_hdr->vendor_id, pci_hdr->device_id, ##__VA_ARGS__)
                                        ^~
vfio/pci.c:482:3: note: in expansion of macro 'pci_dev_warn'
   pci_dev_warn(&vdev->pci.hdr, "%s: BAR4\n", __func__);

This is caused by the operator precedence rules in C, where pointer
deference via "->" has a higher precedence than taking the address with the
ampersand symbol. When the macro is substituted, it becomes
&vdev->pci.hdr->vendor_id and it dereferences vdev->pci.hdr, which is not a
pointer, instead of dereferencing &vdev->pci.hdr, which is a pointer, and
quite likely what the author intended.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 include/kvm/pci.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/include/kvm/pci.h b/include/kvm/pci.h
index 0f2d5bb..d6eb398 100644
--- a/include/kvm/pci.h
+++ b/include/kvm/pci.h
@@ -13,15 +13,15 @@ 
 #include "kvm/kvm-arch.h"
 
 #define pci_dev_err(pci_hdr, fmt, ...) \
-	pr_err("[%04x:%04x] " fmt, pci_hdr->vendor_id, pci_hdr->device_id, ##__VA_ARGS__)
+	pr_err("[%04x:%04x] " fmt, (pci_hdr)->vendor_id, (pci_hdr)->device_id, ##__VA_ARGS__)
 #define pci_dev_warn(pci_hdr, fmt, ...) \
-	pr_warning("[%04x:%04x] " fmt, pci_hdr->vendor_id, pci_hdr->device_id, ##__VA_ARGS__)
+	pr_warning("[%04x:%04x] " fmt, (pci_hdr)->vendor_id, (pci_hdr)->device_id, ##__VA_ARGS__)
 #define pci_dev_info(pci_hdr, fmt, ...) \
-	pr_info("[%04x:%04x] " fmt, pci_hdr->vendor_id, pci_hdr->device_id, ##__VA_ARGS__)
+	pr_info("[%04x:%04x] " fmt, (pci_hdr)->vendor_id, (pci_hdr)->device_id, ##__VA_ARGS__)
 #define pci_dev_dbg(pci_hdr, fmt, ...) \
-	pr_debug("[%04x:%04x] " fmt, pci_hdr->vendor_id, pci_hdr->device_id, ##__VA_ARGS__)
+	pr_debug("[%04x:%04x] " fmt, (pci_hdr)->vendor_id, (pci_hdr)->device_id, ##__VA_ARGS__)
 #define pci_dev_die(pci_hdr, fmt, ...) \
-	die("[%04x:%04x] " fmt, pci_hdr->vendor_id, pci_hdr->device_id, ##__VA_ARGS__)
+	die("[%04x:%04x] " fmt, (pci_hdr)->vendor_id, (pci_hdr)->device_id, ##__VA_ARGS__)
 
 /*
  * PCI Configuration Mechanism #1 I/O ports. See Section 3.7.4.1.