linux-kernel - [PATCH -next v2 2/3] cacheinfo: Make default acpi_get_cache

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Message-Id: <20230124154053.355376-3-pierre.gondois@arm.com>
Date:   Tue, 24 Jan 2023 16:40:47 +0100
From:   Pierre Gondois <pierre.gondois@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Dan Carpenter <error27@...il.com>,
        Pierre Gondois <pierre.gondois@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Akihiko Odaki <akihiko.odaki@...nix.com>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Gavin Shan <gshan@...hat.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH -next v2 2/3] cacheinfo: Make default acpi_get_cache_info() return an error

commit bd500361a937 ("ACPI: PPTT: Update acpi_find_last_cache_level()
to acpi_get_cache_info()")
updates the prototype of acpi_get_cache_info(). The cache 'levels'
is update through a pointer and not the return value of the function.

If CONFIG_ACPI_PPTT is not defined, acpi_get_cache_info() doesn't
update its *levels and *split_levels parameters and returns 0.
This can lead to a faulty behaviour.

Make acpi_get_cache_info() return an error code if CONFIG_ACPI_PPTT
is not defined.
Also,

In init_cache_level(), if no PPTT is present or CONFIG_ACPI_PPTT is
not defined, instead of aborting if acpi_get_cache_info() returns an
error code, just continue. This allows to try fetching the cache
information from clidr_el1.

Signed-off-by: Pierre Gondois <pierre.gondois@....com>
---
 arch/arm64/kernel/cacheinfo.c | 2 +-
 include/linux/cacheinfo.h     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index d3fe9542c370..bf348b8d321f 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -59,7 +59,7 @@ int init_cache_level(unsigned int cpu)
 	} else {
 		ret = acpi_get_cache_info(cpu, &fw_level, NULL);
 		if (ret < 0)
-			return ret;
+			fw_level = 0;
 	}
 
 	if (fw_level < 0)
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index dfef57077cd0..908e19d17f49 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -100,7 +100,7 @@ static inline
 int acpi_get_cache_info(unsigned int cpu,
 			unsigned int *levels, unsigned int *split_levels)
 {
-	return 0;
+	return -ENOENT;
 }
 #else
 int acpi_get_cache_info(unsigned int cpu,
-- 
2.25.1