fbt:kernel:breadn_flags:entry): invalid address (0x0) in action #7

[Samuel Lepetit]

I suspect the easiest way here is just to check that your credential in args[6] is non-null in a predicate.

- Samuel Lepetit
- slepetit at apple.com <mailto:slepetit at apple.com>

> On 18 May 2017, at 13:20, Andreas Longwitz <longwitz at incore.de> wrote:
> 
> Now running FreeBSD 10.3-STABLE #0 r317936 I try to understand the
> problem described in
> 
> https://lists.freebsd.org/pipermail/freebsd-fs/2013-November/018610.html
> 
> using DTrace. Therefore I like to use the probe
> 
>       fbt:kernel:breadn_flags:entry
> 
> to see what is happening in ffs_vgetf() in source ffs_vfsops.c:
> 
>  #define bread(vp, blkno, size, cred, bpp) \
>     breadn_flags(vp, blkno, size, NULL, NULL, 0, cred, 0, bpp)
> 
>  /* Read in the disk contents for the inode, copy into the inode. */
>  error = bread(ump->um_devvp, fsbtodb(fs, ino_to_fsba(fs, ino)),
>              (int)fs->fs_bsize, NOCRED, &bp);
> 
> I get the error
> 
> dtrace: error on enabled probe ID 22 (ID 31371:
> fbt:kernel:breadn_flags:entry): invalid address (0x0) in action #6
> 
> probably because NOCRED is NULL:
> 
>  #define   NOCRED  ((struct ucred *)0)
> 
> I like to know if this case can be handled in DTrace, the parameter
> 
>  args[6]: struct ucred *
> 
> is sometimes a pointer and sometimes NOCRED.
> 
> 
> -- 
> Dr. Andreas Longwitz
> 
> _______________________________________________
> freebsd-dtrace at freebsd.org mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-dtrace
> To unsubscribe, send any mail to "freebsd-dtrace-unsubscribe at freebsd.org"