Re: ktrwriteraw & vget

[Martin Pieuchot]

On 16/03/20(Mon) 14:01, Martin Pieuchot wrote:
> vget(9) might fail, stop right away if that happens.
> 
> CID 1453020 Unchecked return value.

Updated diff that stops tracing if vget(9) fails, similar to what's
currently done if VOP_WRITE(9) fails, suggested by visa@.

Code shuffling is there to avoid calling vput(9) if vget(9) doesn't
succeed.

ok?

Index: kern/kern_ktrace.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_ktrace.c,v
retrieving revision 1.100
diff -u -p -r1.100 kern_ktrace.c
--- kern/kern_ktrace.c  6 Oct 2019 16:24:14 -0000       1.100
+++ kern/kern_ktrace.c  17 Mar 2020 09:46:03 -0000
@@ -649,12 +649,17 @@ ktrwriteraw(struct proc *curp, struct vn
                        auio.uio_iovcnt++;
                auio.uio_resid += kth->ktr_len;
        }
-       vget(vp, LK_EXCLUSIVE | LK_RETRY);
+       error = vget(vp, LK_EXCLUSIVE | LK_RETRY);
+       if (error)
+               goto bad;
        error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, cred);
-       if (!error) {
-               vput(vp);
-               return (0);
-       }
+       vput(vp);
+       if (error)
+               goto bad;
+
+       return (0);
+
+bad:
        /*
         * If error encountered, give up tracing on this vnode.
         */
@@ -663,8 +668,6 @@ ktrwriteraw(struct proc *curp, struct vn
        LIST_FOREACH(pr, &allprocess, ps_list)
                if (pr->ps_tracevp == vp && pr->ps_tracecred == cred)
                        ktrcleartrace(pr);
-
-       vput(vp);
        return (error);
 }