From: Sudeep Holla <sudeep.holla@arm.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Sudeep Holla <sudeep.holla@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
Will Deacon <Will.Deacon@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 9/9] ARM: kernel: add outer cache support for cacheinfo implementation
Date: Thu, 26 Jun 2014 14:02:58 +0100 [thread overview]
Message-ID: <53AC1A02.2040704@arm.com> (raw)
In-Reply-To: <20140625223748.GM32514@n2100.arm.linux.org.uk>
Hi Russell,
On 25/06/14 23:37, Russell King - ARM Linux wrote:
> On Wed, Jun 25, 2014 at 06:30:44PM +0100, Sudeep Holla wrote:
>> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
>> index efc5cab..30ca151 100644
>> --- a/arch/arm/mm/cache-l2x0.c
>> +++ b/arch/arm/mm/cache-l2x0.c
>> @@ -105,6 +105,15 @@ static inline void l2c_unlock(void __iomem *base, unsigned num)
>> }
>> }
>>
>> +static void l2x0_getinfo(struct outer_cache_info *info)
>> +{
>> + if (!info)
>> + return;
>
> Pointless NULL test. If someone passes NULL to this function (which
> you never do in this file) then we want to know about it because _that_
> is a kernel bug - it is invalid to pass NULL. Hence the kernel should
> oops.
>
> Please, don't go around adding stupid NULL tests for conditions which
> should _never_ happen, instead, rely on the kernel to oops if these
> invalid conditions occur. That's why we produce a backtrace from such
> events, to allow invalid conditions to be debugged and fixed.
>
> Having stuff silently ignore in this way does not detect these bugs so
> they go by unnoticed.
>
> Take a moment to read some of the fs/ or kernel/ code, and you'll find
> a lack of NULL checks in there. That's what gives that code performance,
> because it's not spending its time doing loads of useless NULL checks.
>
Understood, will get rid of it.
>> @@ -894,6 +903,7 @@ static void __init __l2c_init(const struct l2c_init_data *data,
>> data->enable(l2x0_base, aux, data->num_lock);
>>
>> outer_cache = fns;
>> + outer_cache.get_info = l2x0_getinfo;
>
> NAK. Think about it.
>
Ah, will specify in l2c_init_data for individual implementations so that
fixups is possible if needed for get_info. Sorry for missing this.
Regards,
Sudeep
next prev parent reply other threads:[~2014-06-26 13:02 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-25 17:30 [PATCH 0/9] drivers: cacheinfo support Sudeep Holla
2014-06-25 17:30 ` [PATCH 1/9] drivers: base: add new class "cpu" to group cpu devices Sudeep Holla
2014-06-25 17:30 ` [PATCH 2/9] drivers: base: support cpu cache information interface to userspace via sysfs Sudeep Holla
2014-06-25 22:23 ` Russell King - ARM Linux
2014-06-26 18:41 ` Sudeep Holla
2014-06-26 18:50 ` Russell King - ARM Linux
2014-06-26 19:03 ` Sudeep Holla
2014-07-10 0:09 ` Greg Kroah-Hartman
2014-07-10 13:37 ` Sudeep Holla
2014-06-25 17:30 ` [PATCH 3/9] ia64: move cacheinfo sysfs to generic cacheinfo infrastructure Sudeep Holla
2014-06-25 17:30 ` [PATCH 4/9] s390: " Sudeep Holla
2014-06-25 17:30 ` [PATCH 5/9] x86: " Sudeep Holla
2014-06-25 17:30 ` [PATCH 6/9] powerpc: " Sudeep Holla
2014-06-25 17:30 ` [PATCH 7/9] ARM64: kernel: add support for cpu cache information Sudeep Holla
2014-06-27 10:36 ` Mark Rutland
2014-06-27 11:22 ` Sudeep Holla
2014-06-27 11:34 ` Mark Rutland
2014-06-25 17:30 ` [PATCH 8/9] ARM: " Sudeep Holla
2014-06-25 22:33 ` Russell King - ARM Linux
2014-06-26 11:33 ` Sudeep Holla
2014-06-26 0:19 ` Stephen Boyd
2014-06-26 11:36 ` Sudeep Holla
2014-06-26 18:45 ` Stephen Boyd
2014-06-27 9:38 ` Sudeep Holla
2014-06-25 17:30 ` [PATCH 9/9] ARM: kernel: add outer cache support for cacheinfo implementation Sudeep Holla
2014-06-25 22:37 ` Russell King - ARM Linux
2014-06-26 13:02 ` Sudeep Holla [this message]
2014-07-25 16:44 ` [PATCH v2 0/9] drivers: cacheinfo support Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 1/9] drivers: base: add new class "cpu" to group cpu devices Sudeep Holla
2014-07-25 19:09 ` Stephen Boyd
2014-07-28 13:37 ` Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 2/9] drivers: base: support cpu cache information interface to userspace via sysfs Sudeep Holla
2014-07-29 23:09 ` Stephen Boyd
2014-07-30 16:23 ` Sudeep Holla
2014-07-31 19:46 ` Stephen Boyd
2014-08-05 18:15 ` Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 3/9] ia64: move cacheinfo sysfs to generic cacheinfo infrastructure Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 4/9] s390: " Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 5/9] x86: " Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 6/9] powerpc: " Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 7/9] ARM64: kernel: add support for cpu cache information Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 8/9] ARM: " Sudeep Holla
2014-07-25 16:44 ` [PATCH v2 9/9] ARM: kernel: add outer cache support for cacheinfo implementation Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 00/11] drivers: cacheinfo support Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 01/11] cpumask: factor out show_cpumap into separate helper function Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 02/11] topology: replace custom attribute macros with standard DEVICE_ATTR* Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 03/11] drivers: base: add new class "cpu" to group cpu devices Sudeep Holla
2014-08-21 11:20 ` David Herrmann
2014-08-21 12:30 ` Sudeep Holla
2014-08-21 12:37 ` David Herrmann
2014-08-21 14:54 ` Sudeep Holla
2014-08-22 9:12 ` Kay Sievers
2014-08-22 11:29 ` [PATCH] drivers: base: add cpu_device_create to support per-cpu devices Sudeep Holla
2014-08-22 11:37 ` David Herrmann
2014-08-22 11:41 ` David Herrmann
2014-08-22 12:33 ` Sudeep Holla
2014-08-26 16:54 ` Sudeep Holla
2014-08-26 17:08 ` David Herrmann
2014-08-22 12:17 ` Sudeep Holla
2014-09-02 17:22 ` Sudeep Holla
2014-09-02 17:26 ` Greg Kroah-Hartman
2014-09-02 17:40 ` Sudeep Holla
2014-09-02 17:55 ` Greg Kroah-Hartman
2014-08-21 10:59 ` [PATCH v3 04/11] drivers: base: support cpu cache information interface to userspace via sysfs Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 05/11] ia64: move cacheinfo sysfs to generic cacheinfo infrastructure Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 06/11] s390: " Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 07/11] x86: " Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 08/11] powerpc: " Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 09/11] ARM64: kernel: add support for cpu cache information Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 10/11] ARM: " Sudeep Holla
2014-08-21 10:59 ` [PATCH v3 11/11] ARM: kernel: add outer cache support for cacheinfo implementation Sudeep Holla
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