The threshold_bank structure is a container for one or more
threshold_block structures. Currently, the container has a single
pointer to the 'first' threshold_block structure which then has a linked
list of the remaining threshold_block structures.

This results in an extra level of indirection where the 'first' block is
checked before iterating over the remaining blocks.

Remove the indirection by including the head of the block list in the
threshold_bank structure which already acts as a container for all the
bank's thresholding blocks.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---

Notes:
    v1->v2:
    * New in v2.

 arch/x86/kernel/cpu/mce/amd.c | 43 ++++++++++++-------------------------------
 1 file changed, 12 insertions(+), 31 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index f8ad40c5c887..df8984aac1c6 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -241,7 +241,8 @@ struct threshold_block {
 
 struct threshold_bank {
 	struct kobject		*kobj;
-	struct threshold_block	*blocks;
+	/* List of threshold blocks within this MCA bank. */
+	struct list_head	miscj;
 };
 
 static DEFINE_PER_CPU(struct threshold_bank **, threshold_banks);
@@ -901,9 +902,9 @@ static void log_and_reset_block(struct threshold_block *block)
  */
 static void amd_threshold_interrupt(void)
 {
-	struct threshold_block *first_block = NULL, *block = NULL, *tmp = NULL;
-	struct threshold_bank **bp = this_cpu_read(threshold_banks);
+	struct threshold_bank **bp = this_cpu_read(threshold_banks), *thr_bank;
 	unsigned int bank, cpu = smp_processor_id();
+	struct threshold_block *block, *tmp;
 
 	/*
 	 * Validate that the threshold bank has been initialized already. The
@@ -917,16 +918,11 @@ static void amd_threshold_interrupt(void)
 		if (!(per_cpu(bank_map, cpu) & BIT_ULL(bank)))
 			continue;
 
-		first_block = bp[bank]->blocks;
-		if (!first_block)
+		thr_bank = bp[bank];
+		if (!thr_bank)
 			continue;
 
-		/*
-		 * The first block is also the head of the list. Check it first
-		 * before iterating over the rest.
-		 */
-		log_and_reset_block(first_block);
-		list_for_each_entry_safe(block, tmp, &first_block->miscj, miscj)
+		list_for_each_entry_safe(block, tmp, &thr_bank->miscj, miscj)
 			log_and_reset_block(block);
 	}
 }
@@ -1145,13 +1141,7 @@ static int allocate_threshold_blocks(unsigned int cpu, struct threshold_bank *tb
 		default_attrs[2] = NULL;
 	}
 
-	INIT_LIST_HEAD(&b->miscj);
-
-	/* This is safe as @tb is not visible yet */
-	if (tb->blocks)
-		list_add(&b->miscj, &tb->blocks->miscj);
-	else
-		tb->blocks = b;
+	list_add(&b->miscj, &tb->miscj);
 
 	err = kobject_init_and_add(&b->kobj, &threshold_ktype, tb->kobj, get_name(cpu, bank, b));
 	if (err)
@@ -1202,6 +1192,8 @@ static int threshold_create_bank(struct threshold_bank **bp, unsigned int cpu,
 		goto out_free;
 	}
 
+	INIT_LIST_HEAD(&b->miscj);
+
 	err = allocate_threshold_blocks(cpu, b, bank, 0, mca_msr_reg(bank, MCA_MISC));
 	if (err)
 		goto out_kobj;
@@ -1222,26 +1214,15 @@ static void threshold_block_release(struct kobject *kobj)
 	kfree(to_block(kobj));
 }
 
-static void deallocate_threshold_blocks(struct threshold_bank *bank)
+static void threshold_remove_bank(struct threshold_bank *bank)
 {
 	struct threshold_block *pos, *tmp;
 
-	list_for_each_entry_safe(pos, tmp, &bank->blocks->miscj, miscj) {
+	list_for_each_entry_safe(pos, tmp, &bank->miscj, miscj) {
 		list_del(&pos->miscj);
 		kobject_put(&pos->kobj);
 	}
 
-	kobject_put(&bank->blocks->kobj);
-}
-
-static void threshold_remove_bank(struct threshold_bank *bank)
-{
-	if (!bank->blocks)
-		goto out_free;
-
-	deallocate_threshold_blocks(bank);
-
-out_free:
 	kobject_put(bank->kobj);
 	kfree(bank);
 }

-- 
2.43.0

> From: Yazen Ghannam <yazen.ghannam@amd.com>
> Sent: Friday, February 14, 2025 12:46 AM
> To: x86@kernel.org; Luck, Tony <tony.luck@intel.com>
> Cc: linux-kernel@vger.kernel.org; linux-edac@vger.kernel.org;
> Smita.KoralahalliChannabasappa@amd.com; Yazen Ghannam
> <yazen.ghannam@amd.com>
> Subject: [PATCH v2 04/16] x86/mce/amd: Put list_head in threshold_bank
> 
> The threshold_bank structure is a container for one or more threshold_block
> structures. Currently, the container has a single pointer to the 'first'
> threshold_block structure which then has a linked list of the remaining
> threshold_block structures.
> 
> This results in an extra level of indirection where the 'first' block is checked
> before iterating over the remaining blocks.
> 
> Remove the indirection by including the head of the block list in the
> threshold_bank structure which already acts as a container for all the bank's
> thresholding blocks.
> 
> Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>

Nice cleanup.

    Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>