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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Nick Desaulniers <ndesaulniers@google.com>,
	Sasha Levin <sashal@kernel.org>,
	Tony Battersby <tonyb@cybernetics.com>
Subject: [PATCH 4.14 15/43] Revert "compiler.h: update definition of unreachable()"
Date: Tue,  2 Jul 2019 10:01:55 +0200	[thread overview]
Message-ID: <20190702080124.581588183@linuxfoundation.org> (raw)
In-Reply-To: <20190702080123.904399496@linuxfoundation.org>

This reverts commit 82017e26e51596ee577171a33f357377ec6513b5, which is
upstream commit fe0640eb30b7da261ae84d252ed9ed3c7e68dfd8.

On Fri, Jun 28, 2019 at 8:53 AM Tony Battersby <tonyb@cybernetics.com> wrote:
>
> Old versions of gcc cannot compile 4.14 since 4.14.113:
>
> ./include/asm-generic/fixmap.h:37: error: implicit declaration of function ‘__builtin_unreachable’
>
> The stable commit that caused the problem is 82017e26e515 ("compiler.h:
> update definition of unreachable()") (upstream commit fe0640eb30b7).
> Reverting the commit fixes the problem.
>
> Kernel 4.17 dropped support for older versions of gcc in upstream commit
> cafa0010cd51 ("Raise the minimum required gcc version to 4.6").  This
> was not backported to 4.14 since that would go against the stable kernel
> rules.
>
> Upstream commit 815f0ddb346c ("include/linux/compiler*.h: make
> compiler-*.h mutually exclusive") was a fix for cafa0010cd51.  This was
> not backported to 4.14.
>
> Upstream commit fe0640eb30b7 ("compiler.h: update definition of
> unreachable()") was a fix for 815f0ddb346c.  This is the commit that was
> backported to 4.14.  But it only fixed a problem introduced in the other
> commits, and without those commits, it ends up introducing a problem
> instead of fixing one.  So I recommend reverting that patch in 4.14,
> which will enable old gcc to compile 4.14 again.  If I understand
> correctly, I believe that clang will still be able to compile 4.14 with
> the patch reverted, although I haven't tried to compile with clang.
>
> The problematic commit is not present in 4.9.x, 4.4.x, 3.18.x, or 3.16.x.

CC: Nick Desaulniers <ndesaulniers@google.com>
CC: Tony Battersby <tonyb@cybernetics.com>,
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/compiler.h | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 67c3934fb9ed..a704d032713b 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -119,10 +119,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 # define ASM_UNREACHABLE
 #endif
 #ifndef unreachable
-# define unreachable() do {		\
-	annotate_unreachable();		\
-	__builtin_unreachable();	\
-} while (0)
+# define unreachable() do { annotate_reachable(); do { } while (1); } while (0)
 #endif
 
 /*
-- 
2.20.1




  parent reply	other threads:[~2019-07-02  8:09 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-02  8:01 [PATCH 4.14 00/43] 4.14.132-stable review Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 01/43] perf ui helpline: Use strlcpy() as a shorter form of strncpy() + explicit set nul Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 02/43] perf help: Remove needless use of strncpy() Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 03/43] perf header: Fix unchecked usage " Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 04/43] Revert "x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP" Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 05/43] IB/hfi1: Close PSM sdma_progress sleep window Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 06/43] block: add a lower-level bio_add_page interface Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 07/43] block: bio_iov_iter_get_pages: pin more pages for multi-segment IOs Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 08/43] 9p/xen: fix check for xenbus_read error in front_probe Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 09/43] 9p/rdma: do not disconnect on down_interruptible EAGAIN Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 10/43] 9p: acl: fix uninitialized iattr access Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 11/43] 9p/rdma: remove useless check in cm_event_handler Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 12/43] 9p: p9dirent_read: check network-provided name length Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 13/43] net/9p: include trans_common.h to fix missing prototype warning Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 14/43] qmi_wwan: Fix out-of-bounds read Greg Kroah-Hartman
2019-07-02  8:01 ` Greg Kroah-Hartman [this message]
2019-07-02  8:01 ` [PATCH 4.14 16/43] fs/proc/array.c: allow reporting eip/esp for all coredumping threads Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 17/43] mm/mempolicy.c: fix an incorrect rebind node in mpol_rebind_nodemask Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 18/43] fs/binfmt_flat.c: make load_flat_shared_library() work Greg Kroah-Hartman
2019-07-02  8:01 ` [PATCH 4.14 19/43] mm/page_idle.c: fix oops because end_pfn is larger than max_pfn Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 20/43] dm log writes: make sure super sector log updates are written in order Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 21/43] scsi: vmw_pscsi: Fix use-after-free in pvscsi_queue_lck() Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 22/43] x86/speculation: Allow guests to use SSBD even if host does not Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 23/43] x86/microcode: Fix the microcode load on CPU hotplug for real Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 24/43] NFS/flexfiles: Use the correct TCP timeout for flexfiles I/O Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 25/43] cpu/speculation: Warn on unsupported mitigations= parameter Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 26/43] eeprom: at24: fix unexpected timeout under high load Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 27/43] af_packet: Block execution of tasks waiting for transmit to complete in AF_PACKET Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 28/43] ipv4: Use return value of inet_iif() for __raw_v4_lookup in the while loop Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 29/43] net/packet: fix memory leak in packet_set_ring() Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 30/43] net: remove duplicate fetch in sock_getsockopt Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 31/43] net: stmmac: fixed new system time seconds value calculation Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 32/43] sctp: change to hold sk after auth shkey is created successfully Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 33/43] tipc: change to use register_pernet_device Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 34/43] tipc: check msg->req data len in tipc_nl_compat_bearer_disable Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 35/43] tun: wake up waitqueues after IFF_UP is set Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 36/43] team: Always enable vlan tx offload Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 37/43] bonding: " Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 38/43] bpf: udp: Avoid calling reuseports bpf_prog from udp_gro Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 39/43] bpf: udp: ipv6: Avoid running reuseports bpf_prog from __udp6_lib_err Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 40/43] arm64: futex: Avoid copying out uninitialised stack in failed cmpxchg() Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 41/43] bpf, arm64: use more scalable stadd over ldxr / stxr loop in xadd Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 42/43] futex: Update comments and docs about return values of arch futex code Greg Kroah-Hartman
2019-07-02  8:02 ` [PATCH 4.14 43/43] tipc: pass tunnel dev as NULL to udp_tunnel(6)_xmit_skb Greg Kroah-Hartman
2019-08-01 10:17   ` Rantala, Tommi T. (Nokia - FI/Espoo)
2019-08-02  7:28     ` gregkh
2019-08-02 11:03       ` Rantala, Tommi T. (Nokia - FI/Espoo)
2019-08-02 11:34         ` gregkh
2019-08-03  0:45         ` Xin Long
2019-08-03  7:11           ` gregkh
2019-07-02 12:12 ` [PATCH 4.14 00/43] 4.14.132-stable review kernelci.org bot
2019-07-02 15:43 ` Naresh Kamboju
2019-07-02 20:22 ` Guenter Roeck
2019-07-02 21:10 ` Kelsey Skunberg
2019-07-02 22:51 ` shuah
2019-07-03 10:20 ` Jon Hunter
2019-07-03 10:20   ` Jon Hunter
2019-07-04  5:26 ` Bharath Vedartham

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