From: Greg KH <gregkh@linuxfoundation.org>
To: "Joseph, Jithu" <jithu.joseph@intel.com>
Cc: hdegoede@redhat.com, markgross@kernel.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
x86@kernel.org, hpa@zytor.com, rostedt@goodmis.org,
ashok.raj@intel.com, tony.luck@intel.com,
linux-kernel@vger.kernel.org,
platform-driver-x86@vger.kernel.org, patches@lists.linux.dev,
ravi.v.shankar@intel.com, thiago.macieira@intel.com,
athenas.jimenez.gonzalez@intel.com, sohil.mehta@intel.com
Subject: Re: [PATCH v2 2/7] platform/x86/intel/ifs: Introduce Array Scan test to IFS
Date: Fri, 17 Feb 2023 10:25:10 +0100 [thread overview]
Message-ID: <Y+9H9otxLYPqMkUh@kroah.com> (raw)
In-Reply-To: <4e5cebd0-815e-e3ca-7068-4d665d337bf2@intel.com>
On Thu, Feb 16, 2023 at 02:57:13PM -0800, Joseph, Jithu wrote:
> On 2/16/2023 4:40 AM, Greg KH wrote:
> >> + ifs_devices[i].data.pkg_auth = kmalloc_array(topology_max_packages(),
> >> + sizeof(bool), GFP_KERNEL);
> >> + if (!ifs_devices[i].data.pkg_auth)
> >> + continue;
> >
> > You have a static array of a structure that contains both things that
> > describe the devices being used, as well as dynamic data with no real
> > lifespan rules. Please don't perputate this common design pattern
> > mistake.
> >
> > Always try to make static data constant and make dynamic data dynamic
> > with proper reference counted lifetime rules. People converting this
> > code into rust in the future will thank you :)
>
> I may not have fully understood your comment. So pardon me if the following description
> on the lifecycle of the dynamic allocated memory is not to the point.
>
> The lifetime of this allocation matches the load time of the driver (allocated on init, freed on exit).
> There are no further / allocations or freeing anywhere within the driver.
> There is only a single place where this memory is used, whose access is serialized via a semaphore.
But the memory is associated with "something" that has a lifetime,
right? This is either a misc device, or a cpu, or a platform device, or
something that you have to determine that you need to allocate it.
So use that as the thing you hang your dynamic data off of, don't use a
static array. Allow that static array to be put into read-only memory
(i.e. it is const and can not be changed by your code accidentally or on
purpose.)
Does that help explain things better?
thanks,
greg k-h
next prev parent reply other threads:[~2023-02-17 9:25 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-31 23:42 [PATCH 0/5] Add Array BIST test support to IFS Jithu Joseph
2023-01-31 23:42 ` [PATCH 1/5] x86/include/asm/msr-index.h: Add IFS Array test bits Jithu Joseph
2023-01-31 23:42 ` [PATCH 2/5] platform/x86/intel/ifs: Introduce Array Scan test to IFS Jithu Joseph
2023-01-31 23:43 ` [PATCH 3/5] platform/x86/intel/ifs: Sysfs interface for Array BIST Jithu Joseph
2023-02-01 5:04 ` Greg KH
2023-02-01 20:55 ` Joseph, Jithu
2023-01-31 23:43 ` [PATCH 4/5] platform/x86/intel/ifs: Implement Array BIST test Jithu Joseph
2023-02-01 5:02 ` Greg KH
2023-02-01 17:22 ` Luck, Tony
2023-02-01 18:19 ` Greg KH
2023-02-01 19:22 ` Tony Luck
2023-02-01 19:35 ` Dave Hansen
2023-02-01 19:43 ` Luck, Tony
2023-02-01 19:53 ` Dave Hansen
2023-02-01 19:45 ` Dave Hansen
2023-02-01 19:56 ` Joseph, Jithu
2023-02-01 20:49 ` Dave Hansen
2023-02-01 21:34 ` Luck, Tony
2023-01-31 23:43 ` [PATCH 5/5] platform/x86/intel/ifs: Trace support for array test Jithu Joseph
2023-02-06 16:40 ` Steven Rostedt
2023-02-06 19:50 ` Joseph, Jithu
2023-02-14 23:44 ` [PATCH v2 0/7] Add Array BIST test support to IFS Jithu Joseph
2023-02-14 23:44 ` [PATCH v2 1/7] x86/include/asm/msr-index.h: Add IFS Array test bits Jithu Joseph
2023-02-14 23:44 ` [PATCH v2 2/7] platform/x86/intel/ifs: Introduce Array Scan test to IFS Jithu Joseph
2023-02-16 12:40 ` Greg KH
2023-02-16 18:46 ` Luck, Tony
2023-02-16 22:57 ` Joseph, Jithu
2023-02-17 9:25 ` Greg KH [this message]
2023-02-14 23:44 ` [PATCH v2 3/7] platform/x86/intel/ifs: Sysfs interface for Array BIST Jithu Joseph
2023-02-14 23:44 ` [PATCH v2 4/7] platform/x86/intel/ifs: Implement Array BIST test Jithu Joseph
2023-02-15 16:58 ` Dave Hansen
2023-02-15 17:11 ` Dave Hansen
2023-02-15 20:22 ` Joseph, Jithu
2023-02-15 20:26 ` Dave Hansen
2023-02-15 21:13 ` Joseph, Jithu
2023-02-15 21:18 ` Dave Hansen
2023-02-22 20:12 ` Dave Hansen
2023-02-22 22:07 ` Joseph, Jithu
2023-02-22 22:28 ` Dave Hansen
2023-02-22 22:36 ` Steven Rostedt
2023-02-22 23:32 ` Joseph, Jithu
2023-02-22 23:59 ` Dave Hansen
2023-02-15 17:44 ` Joseph, Jithu
2023-02-14 23:44 ` [PATCH v2 5/7] platform/x86/intel/ifs: Trace support for array test Jithu Joseph
2023-02-16 0:56 ` Steven Rostedt
2023-02-14 23:44 ` [PATCH v2 6/7] platform/x86/intel/ifs: Update IFS doc Jithu Joseph
2023-02-14 23:44 ` [PATCH v2 7/7] Documentation/ABI: Update IFS ABI doc Jithu Joseph
2023-03-01 1:59 ` [PATCH v3 0/8] Add Array BIST test support to IFS Jithu Joseph
2023-03-01 1:59 ` [PATCH v3 1/8] platform/x86/intel/ifs: Reorganize driver data Jithu Joseph
2023-03-13 14:46 ` Hans de Goede
2023-03-13 21:34 ` Joseph, Jithu
2023-03-16 9:43 ` Hans de Goede
2023-03-01 1:59 ` [PATCH v3 2/8] platform/x86/intel/ifs: IFS cleanup Jithu Joseph
2023-03-13 15:02 ` Hans de Goede
2023-03-01 1:59 ` [PATCH v3 3/8] x86/include/asm/msr-index.h: Add IFS Array test bits Jithu Joseph
2023-03-13 15:03 ` Hans de Goede
2023-03-01 1:59 ` [PATCH v3 4/8] platform/x86/intel/ifs: Introduce Array Scan test to IFS Jithu Joseph
2023-03-13 16:10 ` Hans de Goede
2023-03-13 16:29 ` Hans de Goede
2023-03-13 17:21 ` Luck, Tony
2023-03-15 19:29 ` Joseph, Jithu
2023-03-16 9:50 ` Hans de Goede
2023-03-16 19:44 ` Joseph, Jithu
2023-03-01 1:59 ` [PATCH v3 5/8] platform/x86/intel/ifs: Sysfs interface for Array BIST Jithu Joseph
2023-03-13 16:14 ` Hans de Goede
2023-03-01 1:59 ` [PATCH v3 6/8] platform/x86/intel/ifs: Implement Array BIST test Jithu Joseph
2023-03-13 16:24 ` Hans de Goede
2023-03-13 16:37 ` Joseph, Jithu
2023-03-16 9:59 ` Hans de Goede
2023-03-16 17:40 ` Joseph, Jithu
2023-03-16 18:11 ` Joseph, Jithu
2023-03-16 19:38 ` Hans de Goede
2023-03-01 1:59 ` [PATCH v3 7/8] platform/x86/intel/ifs: Update IFS doc Jithu Joseph
2023-03-01 1:59 ` [PATCH v3 8/8] Documentation/ABI: Update IFS ABI doc Jithu Joseph
2023-03-07 11:02 ` [PATCH v3 0/8] Add Array BIST test support to IFS Hans de Goede
2023-03-22 0:33 ` [PATCH v4 0/9] " Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 1/9] platform/x86/intel/ifs: Separate ifs_pkg_auth from ifs_data Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 2/9] platform/x86/intel/ifs: Reorganize driver data Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 3/9] platform/x86/intel/ifs: IFS cleanup Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 4/9] x86/include/asm/msr-index.h: Add IFS Array test bits Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 5/9] platform/x86/intel/ifs: Introduce Array Scan test to IFS Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 6/9] platform/x86/intel/ifs: Sysfs interface for Array BIST Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 7/9] platform/x86/intel/ifs: Implement Array BIST test Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 8/9] platform/x86/intel/ifs: Update IFS doc Jithu Joseph
2023-03-22 0:33 ` [PATCH v4 9/9] Documentation/ABI: Update IFS ABI doc Jithu Joseph
2023-03-27 13:10 ` [PATCH v4 0/9] Add Array BIST test support to IFS Hans de Goede
2023-04-07 1:49 ` Pengfei Xu
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