On 08/27/2014 10:15 AM, Pádraig Brady wrote:
> On 08/27/2014 03:08 PM, Fridolin Pokorny wrote:
>> diff --git a/lib/mountlist.c b/lib/mountlist.c
>
> Cool, this fits well.
> It would be good to mention the functionality and
> performance benefits in the changelog.
>
>> +#ifdef MOUNTED_PROC_MOUNTINFO
>> +static const char *
>> +mountinfo_path (void) {
>> + static char filename[sizeof ("/proc//mountinfo") + 13]; /* 13 to hold a
>> PID */The magic number 13 is gross, compared to using <intprops.h> from gnulib and using INT_STRLEN_BOUND(pid_t) (which should evaluate to 13) instead. >> + >> + sprintf (filename, "/proc/%u/mountinfo", getpid ()); >> + >> + return filename; >> +} > > I dislike the above as it precludes concurrent usage. > You could avoid that issue by allocating on the heap, or by setting up a witness so that sprintf is called only once by the first caller, and all later callers wait until the first caller is complete. > but can't this be simplified by using /proc/self/mountinfo ? The argument here was that the kernel is slightly slower in order to resolve the symlink of /proc/self in all cases - but is that penalty going to be noticeable? -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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