| Message ID | 20230124154053.355376-3-pierre.gondois@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | cacheinfo: Fix misbehaviours around init_cache_level() | expand |
On Tue, Jan 24, 2023 at 04:40:47PM +0100, Pierre Gondois wrote: > 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. Again, dunno jack about clidr_el1. But the change here seems sane once more? I was going to suggest throwing away ret entirely and just initialising fw_level to zero, since the function inside acpi_get_cache_level() that actually modifies it comes after the last error return anyway - but that probably would just leave you exposed to a change in the core code that doesn't also update the callsites. Plus this looks more deliberate IMO. On that basis, LGTM. > Signed-off-by: Pierre Gondois <pierre.gondois@arm.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 >
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,
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@arm.com> --- arch/arm64/kernel/cacheinfo.c | 2 +- include/linux/cacheinfo.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)