Date: Thu, 18 May 2017 13:34:43 -0700 From: Samuel Lepetit <slepetit@apple.com> To: Andreas Longwitz <longwitz@incore.de> Cc: freebsd-dtrace@freebsd.org Subject: Re: fbt:kernel:breadn_flags:entry): invalid address (0x0) in action #7 Message-ID: <6A020677-BC76-41E1-8372-10B7962F4EDE@apple.com> In-Reply-To: <591E01F5.8080208@incore.de> References: <591E01F5.8080208@incore.de>
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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@apple.com <mailto:slepetit@apple.com> > On 18 May 2017, at 13:20, Andreas Longwitz <longwitz@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@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-dtrace > To unsubscribe, send any mail to "freebsd-dtrace-unsubscribe@freebsd.org"
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