From: Peter Zijlstra <peterz@infradead.org>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Trond Myklebust <trondmy@hammerspace.com>,
"mark.rutland@arm.com" <mark.rutland@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"ralf@linux-mips.org" <ralf@linux-mips.org>,
"jlayton@kernel.org" <jlayton@kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"bfields@fieldses.org" <bfields@fieldses.org>,
"linux-mips@linux-mips.org" <linux-mips@linux-mips.org>,
"linux@roeck-us.net" <linux@roeck-us.net>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"will.deacon@arm.com" <will.deacon@arm.com>,
"boqun.feng@gmail.com" <boqun.feng@gmail.com>,
"paul.burton@mips.com" <paul.burton@mips.com>,
"anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
"jhogan@kernel.org" <jhogan@kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"arnd@arndb.de" <arnd@arndb.de>,
"paulus@samba.org" <paulus@samba.org>,
"mpe@ellerman.id.au" <mpe@ellerman.id.au>,
"benh@kernel.crashing.org" <benh@kernel.crashing.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
dvyukov@google.com
Subject: Re: [RFC PATCH] lib: Introduce generic __cmpxchg_u64() and use it where needed
Date: Mon, 5 Nov 2018 11:38:57 +0100 [thread overview]
Message-ID: <20181105103857.GB22431@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <5a846924-e642-d9d1-4e0e-810bd4d01c26@virtuozzo.com>
On Fri, Nov 02, 2018 at 07:19:15PM +0300, Andrey Ryabinin wrote:
> UBSAN warns about signed overflows despite -fno-strict-overflow if gcc
> version is < 8. I have learned recently that UBSAN in GCC 8 ignores
> signed overflows if -fno-strict-overflow of fwrapv is used.
Ah, good.
> We can always just drop -fsanitize=signed-integer-overflow if it considered too noisy.
I think that is the most consistent beahviour. signed overflow is not UB
in the kernel.
> Although it did catch some real bugs.
If we want an over/under-flow checker, then that should be a separate
plugin and not specific to signed or unsigned.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
"linux-mips@linux-mips.org" <linux-mips@linux-mips.org>,
"will.deacon@arm.com" <will.deacon@arm.com>,
"bfields@fieldses.org" <bfields@fieldses.org>,
"paulus@samba.org" <paulus@samba.org>,
Trond Myklebust <trondmy@hammerspace.com>,
"jhogan@kernel.org" <jhogan@kernel.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
"linux@roeck-us.net" <linux@roeck-us.net>,
"arnd@arndb.de" <arnd@arndb.de>,
"boqun.feng@gmail.com" <boqun.feng@gmail.com>,
dvyukov@google.com,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"jlayton@kernel.org" <jlayton@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"ralf@linux-mips.org" <ralf@linux-mips.org>,
"anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
"paul.burton@mips.com" <paul.burton@mips.com>,
"akpm@linu
Subject: Re: [RFC PATCH] lib: Introduce generic __cmpxchg_u64() and use it where needed
Date: Mon, 5 Nov 2018 11:38:57 +0100 [thread overview]
Message-ID: <20181105103857.GB22431@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <5a846924-e642-d9d1-4e0e-810bd4d01c26@virtuozzo.com>
On Fri, Nov 02, 2018 at 07:19:15PM +0300, Andrey Ryabinin wrote:
> UBSAN warns about signed overflows despite -fno-strict-overflow if gcc
> version is < 8. I have learned recently that UBSAN in GCC 8 ignores
> signed overflows if -fno-strict-overflow of fwrapv is used.
Ah, good.
> We can always just drop -fsanitize=signed-integer-overflow if it considered too noisy.
I think that is the most consistent beahviour. signed overflow is not UB
in the kernel.
> Although it did catch some real bugs.
If we want an over/under-flow checker, then that should be a separate
plugin and not specific to signed or unsigned.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
"linux-mips@linux-mips.org" <linux-mips@linux-mips.org>,
"will.deacon@arm.com" <will.deacon@arm.com>,
"bfields@fieldses.org" <bfields@fieldses.org>,
"paulus@samba.org" <paulus@samba.org>,
Trond Myklebust <trondmy@hammerspace.com>,
"jhogan@kernel.org" <jhogan@kernel.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
"linux@roeck-us.net" <linux@roeck-us.net>,
"arnd@arndb.de" <arnd@arndb.de>,
"boqun.feng@gmail.com" <boqun.feng@gmail.com>,
dvyukov@google.com,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"jlayton@kernel.org" <jlayton@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"ralf@linux-mips.org" <ralf@linux-mips.org>,
"anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
"paul.burton@mips.com" <paul.burton@mips.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"davem@davemloft.net" <davem@davemloft.net>
Subject: Re: [RFC PATCH] lib: Introduce generic __cmpxchg_u64() and use it where needed
Date: Mon, 5 Nov 2018 11:38:57 +0100 [thread overview]
Message-ID: <20181105103857.GB22431@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <5a846924-e642-d9d1-4e0e-810bd4d01c26@virtuozzo.com>
On Fri, Nov 02, 2018 at 07:19:15PM +0300, Andrey Ryabinin wrote:
> UBSAN warns about signed overflows despite -fno-strict-overflow if gcc
> version is < 8. I have learned recently that UBSAN in GCC 8 ignores
> signed overflows if -fno-strict-overflow of fwrapv is used.
Ah, good.
> We can always just drop -fsanitize=signed-integer-overflow if it considered too noisy.
I think that is the most consistent beahviour. signed overflow is not UB
in the kernel.
> Although it did catch some real bugs.
If we want an over/under-flow checker, then that should be a separate
plugin and not specific to signed or unsigned.
next prev parent reply other threads:[~2018-11-05 10:41 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-31 19:52 [RFC PATCH] lib: Introduce generic __cmpxchg_u64() and use it where needed Guenter Roeck
2018-10-31 19:52 ` Guenter Roeck
2018-10-31 21:32 ` Paul Burton
2018-10-31 21:32 ` Paul Burton
2018-10-31 22:02 ` Guenter Roeck
2018-10-31 22:02 ` Guenter Roeck
2018-10-31 23:32 ` Paul Burton
2018-10-31 23:32 ` Paul Burton
2018-11-01 0:17 ` Trond Myklebust
2018-11-01 0:17 ` Trond Myklebust
2018-11-01 0:17 ` Trond Myklebust
2018-11-01 13:18 ` Mark Rutland
2018-11-01 13:18 ` Mark Rutland
2018-11-01 13:18 ` Mark Rutland
2018-11-01 14:59 ` Peter Zijlstra
2018-11-01 14:59 ` Peter Zijlstra
2018-11-01 14:59 ` Peter Zijlstra
2018-11-01 15:22 ` Trond Myklebust
2018-11-01 15:22 ` Trond Myklebust
2018-11-01 15:22 ` Trond Myklebust
2018-11-01 16:32 ` Peter Zijlstra
2018-11-01 16:32 ` Peter Zijlstra
2018-11-01 16:32 ` Peter Zijlstra
2018-11-01 16:59 ` Eric Dumazet
2018-11-01 16:59 ` Eric Dumazet
2018-11-01 16:59 ` Eric Dumazet
2018-11-01 17:14 ` Peter Zijlstra
2018-11-01 17:14 ` Peter Zijlstra
2018-11-01 17:14 ` Peter Zijlstra
2018-11-01 17:27 ` Peter Zijlstra
2018-11-01 17:27 ` Peter Zijlstra
2018-11-01 17:27 ` Peter Zijlstra
2018-11-01 20:29 ` Paul E. McKenney
2018-11-01 20:29 ` Paul E. McKenney
2018-11-01 20:29 ` Paul E. McKenney
2018-11-01 21:38 ` Peter Zijlstra
2018-11-01 21:38 ` Peter Zijlstra
2018-11-01 21:38 ` Peter Zijlstra
2018-11-01 22:26 ` Paul E. McKenney
2018-11-01 22:26 ` Paul E. McKenney
2018-11-01 22:26 ` Paul E. McKenney
2018-11-01 17:43 ` Paul E. McKenney
2018-11-01 17:43 ` Paul E. McKenney
2018-11-01 17:43 ` Paul E. McKenney
2018-11-01 17:01 ` Paul E. McKenney
2018-11-01 17:01 ` Paul E. McKenney
2018-11-01 17:01 ` Paul E. McKenney
2018-11-01 17:18 ` Peter Zijlstra
2018-11-01 17:18 ` Peter Zijlstra
2018-11-01 17:18 ` Peter Zijlstra
2018-11-01 17:34 ` Paul E. McKenney
2018-11-01 17:34 ` Paul E. McKenney
2018-11-01 17:34 ` Paul E. McKenney
2018-11-01 17:46 ` Dmitry Vyukov
2018-11-01 17:46 ` Dmitry Vyukov
2018-11-01 17:46 ` Dmitry Vyukov
2018-11-01 21:45 ` Peter Zijlstra
2018-11-01 21:45 ` Peter Zijlstra
2018-11-01 21:45 ` Peter Zijlstra
2018-11-02 10:56 ` David Laight
2018-11-02 10:56 ` David Laight
2018-11-02 10:56 ` David Laight
2018-11-02 12:23 ` Peter Zijlstra
2018-11-02 12:23 ` Peter Zijlstra
2018-11-02 12:23 ` Peter Zijlstra
2018-11-02 13:38 ` Paul E. McKenney
2018-11-02 13:38 ` Paul E. McKenney
2018-11-02 13:38 ` Paul E. McKenney
2018-11-02 13:37 ` Paul E. McKenney
2018-11-02 13:37 ` Paul E. McKenney
2018-11-02 13:37 ` Paul E. McKenney
2018-11-02 16:19 ` Andrey Ryabinin
2018-11-02 16:19 ` Andrey Ryabinin
2018-11-02 16:19 ` Andrey Ryabinin
2018-11-05 10:38 ` Peter Zijlstra [this message]
2018-11-05 10:38 ` Peter Zijlstra
2018-11-05 10:38 ` Peter Zijlstra
2018-11-05 14:24 ` Peter Zijlstra
2018-11-05 14:24 ` Peter Zijlstra
2018-11-05 14:24 ` Peter Zijlstra
2018-11-01 17:51 ` [PATCH] SUNRPC: Use atomic(64)_t for seq_send(64) Paul Burton
2018-11-01 17:57 ` Trond Myklebust
2018-11-01 17:54 ` [RFC PATCH] lib: Introduce generic __cmpxchg_u64() and use it where needed Paul Burton
2018-11-01 17:54 ` Paul Burton
2018-11-01 17:54 ` Paul Burton
2018-11-01 17:54 ` Paul Burton
2018-11-01 1:18 ` Guenter Roeck
2018-11-01 1:18 ` Guenter Roeck
2018-11-01 6:30 ` Trond Myklebust
2018-11-01 6:30 ` Trond Myklebust
2018-11-01 6:30 ` Trond Myklebust
2018-11-01 15:28 ` Guenter Roeck
2018-11-01 15:28 ` Guenter Roeck
2018-11-01 15:28 ` Guenter Roeck
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