linux-kernel - Re: linux-next: Tree for Dec 6 (objtool, lots in btrfs)

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Message-ID: <20191214054515.ougsr5ykhl3vvy57@treble>
Date:   Fri, 13 Dec 2019 23:45:15 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     dsterba@...e.cz, Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Btrfs <linux-btrfs@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: linux-next: Tree for Dec 6 (objtool, lots in btrfs)

On Fri, Dec 13, 2019 at 04:04:58PM -0800, Randy Dunlap wrote:
> > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> > index b2e8fd8a8e59..bbd68520f5f1 100644
> > --- a/fs/btrfs/ctree.h
> > +++ b/fs/btrfs/ctree.h
> > @@ -3110,14 +3110,16 @@ do {								\
> >  	rcu_read_unlock();					\
> >  } while (0)
> >  
> > -__cold
> > +#ifdef CONFIG_BTRFS_ASSERT
> > +__cold __unlikely
> 
> what provides __unlikely?  It is causing build errors.
> 
> and if I remove the "__unlikely", I still see the objtool warnings
> (unreachable instructions).

Ha, not sure how that happened... Should be __noreturn instead of
__unlikely.  Cheers...

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b2e8fd8a8e59..398bd010dfc5 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3110,14 +3110,16 @@ do {								\
 	rcu_read_unlock();					\
 } while (0)
 
-__cold
+#ifdef CONFIG_BTRFS_ASSERT
+__cold __noreturn
 static inline void assfail(const char *expr, const char *file, int line)
 {
-	if (IS_ENABLED(CONFIG_BTRFS_ASSERT)) {
-		pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
-		BUG();
-	}
+	pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
+	BUG();
 }
+#else
+static inline void assfail(const char *expr, const char *file, int line) {}
+#endif
 
 #define ASSERT(expr)	\
 	(likely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))