[tip: x86/cache] x86/resctrl: Use __set_bit()/__clear_bit() instead of open coding

tip-bot2 for James Morse
2024-02-19T18:37:36Z

The following commit has been merged into the x86/cache branch of tip:

Commit-ID: 5d920b6881f2249be3a028ce0a7f31c5cc61b1ee
Gitweb: https://git.kernel.org/tip/5d920b6881f2249be3a028ce0a7f31c5cc61b1ee
Author: James Morse <james.morse@arm.com>
AuthorDate: Tue, 13 Feb 2024 18:44:23
Committer: Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Fri, 16 Feb 2024 19:18:31 +01:00

x86/resctrl: Use __set_bit()/__clear_bit() instead of open coding

The resctrl CLOSID allocator uses a single 32bit word to track which
CLOSID are free. The setting and clearing of bits is open coded.

Convert the existing open coded bit manipulations of closid_free_map
to use __set_bit() and friends. These don't need to be atomic as this
list is protected by the mutex.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-10-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index dcffd1c..bc6e0f8 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -111,7 +111,7 @@ void rdt_staged_configs_clear(void)
* - Our choices on how to configure each resource become progressively more
* limited as the number of resources grows.
*/
-static int closid_free_map;
+static unsigned long closid_free_map;
static int closid_free_map_len;

int closids_supported(void)
@@ -130,8 +130,8 @@ static void closid_init(void)

closid_free_map = BIT_MASK(rdt_min_closid) - 1;

- /* CLOSID 0 is always reserved for the default group */
- closid_free_map &= ~1;
+ /* RESCTRL_RESERVED_CLOSID is always reserved for the default group */
+ __clear_bit(RESCTRL_RESERVED_CLOSID, &closid_free_map);
closid_free_map_len = rdt_min_closid;
}

@@ -139,17 +139,21 @@ static int closid_alloc(void)
{
u32 closid = ffs(closid_free_map);

+ lockdep_assert_held(&rdtgroup_mutex);
+
if (closid == 0)
return -ENOSPC;
closid--;
- closid_free_map &= ~(1 << closid);
+ __clear_bit(closid, &closid_free_map);

return closid;
}

void closid_free(int closid)
{
- closid_free_map |= 1 << closid;
+ lockdep_assert_held(&rdtgroup_mutex);
+
+ __set_bit(closid, &closid_free_map);
}

/**
@@ -161,7 +165,9 @@ void closid_free(int closid)
*/
static bool closid_allocated(unsigned int closid)
{
- return (closid_free_map & (1 << closid)) == 0;
+ lockdep_assert_held(&rdtgroup_mutex);
+
+ return !test_bit(closid, &closid_free_map);
}

/**