From: Andreas Schwab <schwab@linux-m68k.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Kyle McMartin <kyle@mcmartin.ca>,
RTCLINUX <rtc-linux@googlegroups.com>,
Alessandro Zummo <a.zummo@towertech.it>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
Parisc List <linux-parisc@vger.kernel.org>,
linux-m68k <linux-m68k@lists.linux-m68k.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/6] rtc: generic: allow building on all architectures
Date: Wed, 02 Mar 2016 10:28:40 +0100 [thread overview]
Message-ID: <mvmwpplns8n.fsf@hawking.suse.de> (raw)
In-Reply-To: <CAMuHMdW5+jZ1n9WnCwBrGSGjUa8ziNTTqf-H15EFTQC_iwnw+Q@mail.gmail.com> (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100")
Geert Uytterhoeven <geert@linux-m68k.org> writes:
>> +#else
>> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL
>> +#endif
>>
>> static int __init generic_rtc_probe(struct platform_device *dev)
>> {
>> struct rtc_device *rtc;
>> + const struct rtc_class_ops *ops;
>> +
>> + ops = dev_get_platdata(&dev->dev);
>> + if (!ops)
>> + ops = &generic_rtc_ops;
>
> I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as
> undefined behavior?
Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If
the operand is the result of a unary * operator, neither that operator
nor the & operator is evaluated and the result is as if both were
omitted).
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
WARNING: multiple messages have this Message-ID (diff)
From: Andreas Schwab <schwab@linux-m68k.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
"linux-arm-kernel\@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Kyle McMartin <kyle@mcmartin.ca>,
RTCLINUX <rtc-linux@googlegroups.com>,
Alessandro Zummo <a.zummo@towertech.it>,
"linuxppc-dev\@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
Parisc List <linux-parisc@vger.kernel.org>,
linux-m68k <linux-m68k@lists.linux-m68k.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/6] rtc: generic: allow building on all architectures
Date: Wed, 02 Mar 2016 10:28:40 +0100 [thread overview]
Message-ID: <mvmwpplns8n.fsf@hawking.suse.de> (raw)
In-Reply-To: <CAMuHMdW5+jZ1n9WnCwBrGSGjUa8ziNTTqf-H15EFTQC_iwnw+Q@mail.gmail.com> (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100")
Geert Uytterhoeven <geert@linux-m68k.org> writes:
>> +#else
>> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL
>> +#endif
>>
>> static int __init generic_rtc_probe(struct platform_device *dev)
>> {
>> struct rtc_device *rtc;
>> + const struct rtc_class_ops *ops;
>> +
>> + ops = dev_get_platdata(&dev->dev);
>> + if (!ops)
>> + ops = &generic_rtc_ops;
>
> I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as
> undefined behavior?
Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If
the operand is the result of a unary * operator, neither that operator
nor the & operator is evaluated and the result is as if both were
omitted).
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
WARNING: multiple messages have this Message-ID (diff)
From: Andreas Schwab <schwab@linux-m68k.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
"linux-arm-kernel\@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Kyle McMartin <kyle@mcmartin.ca>,
RTCLINUX <rtc-linux@googlegroups.com>,
Alessandro Zummo <a.zummo@towertech.it>,
"linuxppc-dev\@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
Parisc List <linux-parisc@vger.kernel.org>,
linux-m68k <linux-m68k@lists.linux-m68k.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [rtc-linux] Re: [PATCH 1/6] rtc: generic: allow building on all architectures
Date: Wed, 02 Mar 2016 10:28:40 +0100 [thread overview]
Message-ID: <mvmwpplns8n.fsf@hawking.suse.de> (raw)
In-Reply-To: <CAMuHMdW5+jZ1n9WnCwBrGSGjUa8ziNTTqf-H15EFTQC_iwnw+Q@mail.gmail.com> (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100")
Geert Uytterhoeven <geert@linux-m68k.org> writes:
>> +#else
>> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL
>> +#endif
>>
>> static int __init generic_rtc_probe(struct platform_device *dev)
>> {
>> struct rtc_device *rtc;
>> + const struct rtc_class_ops *ops;
>> +
>> + ops = dev_get_platdata(&dev->dev);
>> + if (!ops)
>> + ops = &generic_rtc_ops;
>
> I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as
> undefined behavior?
Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If
the operand is the result of a unary * operator, neither that operator
nor the & operator is evaluated and the result is as if both were
omitted).
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
--
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WARNING: multiple messages have this Message-ID (diff)
From: Andreas Schwab <schwab@linux-m68k.org>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/6] rtc: generic: allow building on all architectures
Date: Wed, 02 Mar 2016 09:28:40 +0000 [thread overview]
Message-ID: <mvmwpplns8n.fsf@hawking.suse.de> (raw)
In-Reply-To: <CAMuHMdW5+jZ1n9WnCwBrGSGjUa8ziNTTqf-H15EFTQC_iwnw+Q@mail.gmail.com> (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100")
Geert Uytterhoeven <geert@linux-m68k.org> writes:
>> +#else
>> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL
>> +#endif
>>
>> static int __init generic_rtc_probe(struct platform_device *dev)
>> {
>> struct rtc_device *rtc;
>> + const struct rtc_class_ops *ops;
>> +
>> + ops = dev_get_platdata(&dev->dev);
>> + if (!ops)
>> + ops = &generic_rtc_ops;
>
> I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as
> undefined behavior?
Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If
the operand is the result of a unary * operator, neither that operator
nor the & operator is evaluated and the result is as if both were
omitted).
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
WARNING: multiple messages have this Message-ID (diff)
From: schwab@linux-m68k.org (Andreas Schwab)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/6] rtc: generic: allow building on all architectures
Date: Wed, 02 Mar 2016 10:28:40 +0100 [thread overview]
Message-ID: <mvmwpplns8n.fsf@hawking.suse.de> (raw)
In-Reply-To: <CAMuHMdW5+jZ1n9WnCwBrGSGjUa8ziNTTqf-H15EFTQC_iwnw+Q@mail.gmail.com> (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100")
Geert Uytterhoeven <geert@linux-m68k.org> writes:
>> +#else
>> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL
>> +#endif
>>
>> static int __init generic_rtc_probe(struct platform_device *dev)
>> {
>> struct rtc_device *rtc;
>> + const struct rtc_class_ops *ops;
>> +
>> + ops = dev_get_platdata(&dev->dev);
>> + if (!ops)
>> + ops = &generic_rtc_ops;
>
> I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as
> undefined behavior?
Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If
the operand is the result of a unary * operator, neither that operator
nor the & operator is evaluated and the result is as if both were
omitted).
Andreas.
--
Andreas Schwab, schwab at linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
WARNING: multiple messages have this Message-ID (diff)
From: Andreas Schwab <schwab@linux-m68k.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>,
"linux-arm-kernel\@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Kyle McMartin <kyle@mcmartin.ca>,
RTCLINUX <rtc-linux@googlegroups.com>,
Alessandro Zummo <a.zummo@towertech.it>,
"linuxppc-dev\@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
Parisc List <linux-parisc@vger.kernel.org>,
linux-m68k <linux-m68k@vger.kernel.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/6] rtc: generic: allow building on all architectures
Date: Wed, 02 Mar 2016 10:28:40 +0100 [thread overview]
Message-ID: <mvmwpplns8n.fsf@hawking.suse.de> (raw)
In-Reply-To: <CAMuHMdW5+jZ1n9WnCwBrGSGjUa8ziNTTqf-H15EFTQC_iwnw+Q@mail.gmail.com> (Geert Uytterhoeven's message of "Wed, 2 Mar 2016 09:57:27 +0100")
Geert Uytterhoeven <geert@linux-m68k.org> writes:
>> +#else
>> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL
>> +#endif
>>
>> static int __init generic_rtc_probe(struct platform_device *dev)
>> {
>> struct rtc_device *rtc;
>> + const struct rtc_class_ops *ops;
>> +
>> + ops = dev_get_platdata(&dev->dev);
>> + if (!ops)
>> + ops = &generic_rtc_ops;
>
> I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as
> undefined behavior?
Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If
the operand is the result of a unary * operator, neither that operator
nor the & operator is evaluated and the result is as if both were
omitted).
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
next prev parent reply other threads:[~2016-03-02 9:28 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-01 16:59 [PATCH 0/6] rtc: generic: follow up for COMPILE_TEST Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` [rtc-linux] " Arnd Bergmann
2016-03-01 16:59 ` [PATCH 1/6] rtc: generic: allow building on all architectures Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` [rtc-linux] " Arnd Bergmann
2016-03-02 8:57 ` Geert Uytterhoeven
2016-03-02 8:57 ` Geert Uytterhoeven
2016-03-02 8:57 ` Geert Uytterhoeven
2016-03-02 8:57 ` Geert Uytterhoeven
2016-03-02 8:57 ` Geert Uytterhoeven
2016-03-02 8:57 ` [rtc-linux] " Geert Uytterhoeven
2016-03-02 9:05 ` Arnd Bergmann
2016-03-02 9:05 ` Arnd Bergmann
2016-03-02 9:05 ` Arnd Bergmann
2016-03-02 9:05 ` Arnd Bergmann
2016-03-02 9:05 ` Arnd Bergmann
2016-03-02 9:05 ` [rtc-linux] " Arnd Bergmann
2016-03-02 9:05 ` Arnd Bergmann
2016-03-02 9:28 ` Andreas Schwab [this message]
2016-03-02 9:28 ` Andreas Schwab
2016-03-02 9:28 ` Andreas Schwab
2016-03-02 9:28 ` Andreas Schwab
2016-03-02 9:28 ` [rtc-linux] " Andreas Schwab
2016-03-02 9:28 ` Andreas Schwab
2016-03-02 9:39 ` Geert Uytterhoeven
2016-03-02 9:39 ` Geert Uytterhoeven
2016-03-02 9:39 ` Geert Uytterhoeven
2016-03-02 9:39 ` Geert Uytterhoeven
2016-03-02 9:39 ` [rtc-linux] " Geert Uytterhoeven
2016-03-02 9:39 ` Geert Uytterhoeven
2016-03-01 16:59 ` [PATCH 2/6] m68k: rtc: provide rtc_class_ops directly Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` [rtc-linux] " Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` [PATCH 3/6] powerpc: " Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` Arnd Bergmann
2016-03-01 16:59 ` [rtc-linux] " Arnd Bergmann
2016-03-01 18:37 ` kbuild test robot
2016-03-01 18:37 ` kbuild test robot
2016-03-01 18:37 ` kbuild test robot
2016-03-01 18:37 ` kbuild test robot
2016-03-01 18:37 ` [rtc-linux] " kbuild test robot
2016-03-01 18:37 ` kbuild test robot
2016-03-01 20:31 ` Arnd Bergmann
2016-03-01 20:31 ` Arnd Bergmann
2016-03-01 20:31 ` Arnd Bergmann
2016-03-01 20:31 ` Arnd Bergmann
2016-03-01 20:31 ` Arnd Bergmann
2016-03-01 20:31 ` [rtc-linux] " Arnd Bergmann
2016-03-01 17:00 ` [PATCH 4/6] parisc: " Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` [rtc-linux] " Arnd Bergmann
2016-03-01 17:19 ` kbuild test robot
2016-03-01 17:19 ` kbuild test robot
2016-03-01 17:19 ` kbuild test robot
2016-03-01 17:19 ` kbuild test robot
2016-03-01 17:19 ` kbuild test robot
2016-03-01 17:19 ` [rtc-linux] " kbuild test robot
2016-03-10 4:34 ` Alexandre Belloni
2016-03-10 4:34 ` Alexandre Belloni
2016-03-10 4:34 ` Alexandre Belloni
2016-03-10 4:34 ` Alexandre Belloni
2016-03-10 4:34 ` [rtc-linux] " Alexandre Belloni
2016-03-01 17:00 ` [PATCH 5/6] sh: " Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` [rtc-linux] " Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` [PATCH 6/6] rtc: generic: remove get_rtc_time/set_rtc_time wrappers Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` Arnd Bergmann
2016-03-01 17:00 ` [rtc-linux] " Arnd Bergmann
2016-03-10 4:41 ` [PATCH 0/6] rtc: generic: follow up for COMPILE_TEST Alexandre Belloni
2016-03-10 4:41 ` Alexandre Belloni
2016-03-10 4:41 ` Alexandre Belloni
2016-03-10 4:41 ` [rtc-linux] " Alexandre Belloni
2016-03-10 4:41 ` Alexandre Belloni
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