linux-kernel - Re: [PATCH] x86/mm: Hide mm_free_global_asid() definition under 'CONFIG_BROADCAST_TLB

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Message-ID: <733058ef2a54dc8323835fc26ca3b402ced5fc7f.camel@surriel.com>
Date: Wed, 14 Jan 2026 10:09:42 -0500
From: Rik van Riel <riel@...riel.com>
To: Hou Wenlong <houwenlong.hwl@...group.com>, linux-kernel@...r.kernel.org
Cc: Thomas Gleixner <tglx@...nel.org>, Ingo Molnar <mingo@...hat.com>, 
 Borislav Petkov	 <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 x86@...nel.org, "H. Peter Anvin"	 <hpa@...or.com>, Andy Lutomirski
 <luto@...nel.org>, Peter Zijlstra	 <peterz@...radead.org>, Andrew Morton
 <akpm@...ux-foundation.org>, Will Deacon	 <will@...nel.org>, Ryan Roberts
 <ryan.roberts@....com>, Jann Horn	 <jannh@...gle.com>, Barry Song
 <baohua@...nel.org>
Subject: Re: [PATCH] x86/mm: Hide mm_free_global_asid() definition under
 'CONFIG_BROADCAST_TLB_FLUSH'

On Wed, 2026-01-14 at 21:21 +0800, Hou Wenlong wrote:
> When 'CONFIG_BROADCAST_TLB_FLUSH' is not enabled,
> mm_free_global_asid()
> remains a globally visible symbol and generates a useless function
> call
> to it in destroy_context(). Therefore, hide the mm_free_global_asid()
> definition under 'CONFIG_BROADCAST_TLB_FLUSH' and provide a static
> inline empty version when it is not enabled to remove the function
> call.
> 
> Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>

This may not create any measurable speedups, since it's
just one no-op function call in the exit path, but it
does reduce the size of the kernel on 32 bit systems where
CONFIG_BROADCAST_TLB_FLUSH is not enabled.

Reviewed-by: Rik van Riel <riel@...riel.com>

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