| Message ID | 1305025653-17138-1-git-send-email-ndevos@redhat.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Tue, 2011-05-10 at 12:07 +0100, Niels de Vos wrote: > When DBG() is used in a simple if-else, the resulting code path > currently depends on the definition of DBG(). Inserting the statement in > a "do { ... } while (0)" prevents this possible misuse. > > Signed-off-by: Niels de Vos <ndevos@redhat.com> Thanks, I'll add this to the dss2 tree. Tomi -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/video/omap2/omapfb/omapfb.h b/drivers/video/omap2/omapfb/omapfb.h index 1305fc9..456c586 100644 --- a/drivers/video/omap2/omapfb/omapfb.h +++ b/drivers/video/omap2/omapfb/omapfb.h @@ -34,8 +34,10 @@ #ifdef DEBUG extern unsigned int omapfb_debug; #define DBG(format, ...) \ - if (omapfb_debug) \ - printk(KERN_DEBUG "OMAPFB: " format, ## __VA_ARGS__) + do { \ + if (omapfb_debug) \ + printk(KERN_DEBUG "OMAPFB: " format, ## __VA_ARGS__); \ + } while (0) #else #define DBG(format, ...) #endif
When DBG() is used in a simple if-else, the resulting code path currently depends on the definition of DBG(). Inserting the statement in a "do { ... } while (0)" prevents this possible misuse. Signed-off-by: Niels de Vos <ndevos@redhat.com> --- V2: add the missing closing } Note, I have not found any offenders, but a mistake can easily be made. The following example shows what can go wrong if little intention is paid to the definition of the DBG() macro. Example: if something_went_wrong() DBG("oh no, something went wrong!\n"); else printk("all went fine\n"); Old result where the else is placed inside the first if-statment: if something_went_wrong() { if (omapfb_debug) { printk(KERN_DEBUG "oh no, something went wrong!\n"); } else { printk("all went fine\n"); } } New result where the else is an alternative to the first if-statement: if something_went_wrong() { do { if (omapfb_debug) printk(KERN_DEBUG "oh no, something went wrong!\n"); } while (0); } else { printk("all went fine\n"); } --- drivers/video/omap2/omapfb/omapfb.h | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-)