From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Alexey Brodkin <alexey.brodkin@synopsys.com>,
Marc Gonzalez <marc.w.gonzalez@free.fr>,
Will Deacon <will@kernel.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Rafael Wysocki <rjw@rjwysocki.net>,
LKML <linux-kernel@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Russell King <rmk+kernel@armlinux.org.uk>,
Mark Brown <broonie@kernel.org>, Tejun Heo <tj@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH v1] devres: align devres.data strictly only for devm_kmalloc()
Date: Fri, 20 Dec 2019 15:16:05 +0100 [thread overview]
Message-ID: <20191220141605.GA2292734@kroah.com> (raw)
In-Reply-To: <20191220140655.GN2827@hirez.programming.kicks-ass.net>
On Fri, Dec 20, 2019 at 03:06:55PM +0100, Peter Zijlstra wrote:
> On Fri, Dec 20, 2019 at 11:19:27AM +0100, Marc Gonzalez wrote:
> > Would anyone else have any suggestions, comments, insights, recommendations,
> > improvements, guidance, or wisdom? :-)
>
> Flip devres upside down!
>
> **WARNING, wear protective glasses when reading the below**
>
>
> struct devres {
> struct devres_node node;
> void *data;
> };
>
> /*
> * We place struct devres at the tail of the memory allocation
> * such that data retains the ARCH_KMALLOC_MINALIGN alignment.
> * struct devres itself is just 4 pointers and should therefore
> * only require trivial alignment.
> */
> static inline struct devres *data2devres(void *data)
> {
> return (struct devres *)(data + ksize(data) - sizeof(struct devres));
> }
>
> void *alloc_dr(...)
> {
> struct devres *dr;
> void *data;
>
> data = kmalloc(size + sizeof(struct devres), GFP_KERNEL);
> dr = data2devres(data);
> WARN_ON((unsigned long)dr & __alignof(*dr)-1);
> INIT_LIST_HEAD(&dr->node.entry);
> dr->node.release = release;
> dr->data = data;
>
> return dr;
> }
>
> void devres_free(void *data)
> {
> if (data) {
> struct devres *dr = data2devres(data);
> BUG_ON(!list_empty(dr->node.entry));
> kfree(data);
> }
> }
>
> static int release_nodes(...)
> {
> ...
> list_for_each_entry_safe_reverse(dr, ...) {
> ...
> kfree(dr->data);
> }
> }
>
Ok, that's my queue to walk away from the keyboard and start drinking, I
think the holiday season has now officially started.
ugh. crazy.
but brilliant :)
greg k-h
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WARNING: multiple messages have this Message-ID (diff)
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Marc Gonzalez <marc.w.gonzalez@free.fr>,
Rafael Wysocki <rjw@rjwysocki.net>,
LKML <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Robin Murphy <robin.murphy@arm.com>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Alexey Brodkin <alexey.brodkin@synopsys.com>,
Will Deacon <will@kernel.org>,
Russell King <rmk+kernel@armlinux.org.uk>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Tejun Heo <tj@kernel.org>, Mark Brown <broonie@kernel.org>
Subject: Re: [RFC PATCH v1] devres: align devres.data strictly only for devm_kmalloc()
Date: Fri, 20 Dec 2019 15:16:05 +0100 [thread overview]
Message-ID: <20191220141605.GA2292734@kroah.com> (raw)
In-Reply-To: <20191220140655.GN2827@hirez.programming.kicks-ass.net>
On Fri, Dec 20, 2019 at 03:06:55PM +0100, Peter Zijlstra wrote:
> On Fri, Dec 20, 2019 at 11:19:27AM +0100, Marc Gonzalez wrote:
> > Would anyone else have any suggestions, comments, insights, recommendations,
> > improvements, guidance, or wisdom? :-)
>
> Flip devres upside down!
>
> **WARNING, wear protective glasses when reading the below**
>
>
> struct devres {
> struct devres_node node;
> void *data;
> };
>
> /*
> * We place struct devres at the tail of the memory allocation
> * such that data retains the ARCH_KMALLOC_MINALIGN alignment.
> * struct devres itself is just 4 pointers and should therefore
> * only require trivial alignment.
> */
> static inline struct devres *data2devres(void *data)
> {
> return (struct devres *)(data + ksize(data) - sizeof(struct devres));
> }
>
> void *alloc_dr(...)
> {
> struct devres *dr;
> void *data;
>
> data = kmalloc(size + sizeof(struct devres), GFP_KERNEL);
> dr = data2devres(data);
> WARN_ON((unsigned long)dr & __alignof(*dr)-1);
> INIT_LIST_HEAD(&dr->node.entry);
> dr->node.release = release;
> dr->data = data;
>
> return dr;
> }
>
> void devres_free(void *data)
> {
> if (data) {
> struct devres *dr = data2devres(data);
> BUG_ON(!list_empty(dr->node.entry));
> kfree(data);
> }
> }
>
> static int release_nodes(...)
> {
> ...
> list_for_each_entry_safe_reverse(dr, ...) {
> ...
> kfree(dr->data);
> }
> }
>
Ok, that's my queue to walk away from the keyboard and start drinking, I
think the holiday season has now officially started.
ugh. crazy.
but brilliant :)
greg k-h
next prev parent reply other threads:[~2019-12-20 14:16 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-17 15:30 [RFC PATCH v1] devres: align devres.data strictly only for devm_kmalloc() Marc Gonzalez
2019-12-17 15:30 ` Marc Gonzalez
2019-12-17 15:45 ` Greg Kroah-Hartman
2019-12-17 15:45 ` Greg Kroah-Hartman
2019-12-17 16:17 ` Marc Gonzalez
2019-12-17 16:17 ` Marc Gonzalez
2019-12-18 14:20 ` Alexey Brodkin
2019-12-18 14:20 ` Alexey Brodkin
2019-12-18 14:20 ` Alexey Brodkin
2019-12-18 15:40 ` Marc Gonzalez
2019-12-18 15:40 ` Marc Gonzalez
2019-12-18 15:40 ` Marc Gonzalez
2019-12-20 10:19 ` Marc Gonzalez
2019-12-20 10:19 ` Marc Gonzalez
2019-12-20 10:22 ` Greg Kroah-Hartman
2019-12-20 10:22 ` Greg Kroah-Hartman
2019-12-20 10:22 ` Greg Kroah-Hartman
2019-12-20 10:22 ` Greg Kroah-Hartman
2019-12-20 12:05 ` Marc Gonzalez
2019-12-20 12:05 ` Marc Gonzalez
2019-12-20 17:19 ` Peter Zijlstra
2019-12-20 17:19 ` Peter Zijlstra
2019-12-20 14:06 ` Peter Zijlstra
2019-12-20 14:06 ` Peter Zijlstra
2019-12-20 14:16 ` Greg Kroah-Hartman [this message]
2019-12-20 14:16 ` Greg Kroah-Hartman
2019-12-20 15:01 ` Robin Murphy
2019-12-20 15:01 ` Robin Murphy
2019-12-20 17:13 ` Peter Zijlstra
2019-12-20 17:13 ` Peter Zijlstra
2019-12-20 22:02 ` Robin Murphy
2019-12-20 22:02 ` Robin Murphy
2020-01-06 10:05 ` Peter Zijlstra
2020-01-06 10:05 ` Peter Zijlstra
2019-12-20 19:32 ` Alexey Brodkin
2019-12-20 19:32 ` Alexey Brodkin
2019-12-20 19:32 ` Alexey Brodkin
2019-12-20 20:23 ` Peter Zijlstra
2019-12-20 20:23 ` Peter Zijlstra
2019-12-20 20:23 ` Peter Zijlstra
2019-12-20 21:02 ` Alexey Brodkin
2019-12-20 21:02 ` Alexey Brodkin
2019-12-20 21:02 ` Alexey Brodkin
2019-12-20 21:47 ` Dmitry Torokhov
2019-12-20 21:47 ` Dmitry Torokhov
2019-12-20 21:47 ` Dmitry Torokhov
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