[PATCH AUTOSEL 5.15 1/2] ethernet: intel: fix building with large NR_CPUS

[PATCH AUTOSEL 5.15 1/2] ethernet: intel: fix building with large NR_CPUS

[Sasha Levin]

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit 24171a5a4a952c26568ff0d2a0bc8c4708a95e1d ]

With large values of CONFIG_NR_CPUS, three Intel ethernet drivers fail to
compile like:

In function ‘i40e_free_q_vector’,
    inlined from ‘i40e_vsi_alloc_q_vectors’ at drivers/net/ethernet/intel/i40e/i40e_main.c:12112:3:
  571 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
include/linux/rcupdate.h:1084:17: note: in expansion of macro ‘BUILD_BUG_ON’
 1084 |                 BUILD_BUG_ON(offsetof(typeof(*(ptr)), rhf) >= 4096);    \
drivers/net/ethernet/intel/i40e/i40e_main.c:5113:9: note: in expansion of macro ‘kfree_rcu’
 5113 |         kfree_rcu(q_vector, rcu);
      |         ^~~~~~~~~

The problem is that the 'rcu' member in 'q_vector' is too far from the start
of the structure. Move this member before the CPU mask instead, in all three
drivers.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Tested-by: Sunitha Mekala <sunithax.d.mekala@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

**YES**

This commit should be backported to stable kernel trees for the
following reasons:

1. **Compilation Failure Fix**: This fixes a build-time compilation
   failure that occurs with large values of CONFIG_NR_CPUS. The error
   prevents the kernel from building successfully, which is a
   significant issue for systems configured with high CPU counts.

2. **Root Cause**: The issue stems from the `kfree_rcu()` macro in
   `include/linux/rcupdate.h:1084` which includes a
   `BUILD_BUG_ON(offsetof(typeof(*(ptr)), rhf) >= 4096)` check. This
   compile-time assertion ensures that the RCU head field is within the
   first 4096 bytes of the structure.

3. **Simple and Safe Fix**: The fix is straightforward - it moves the
   `struct rcu_head rcu` member earlier in the structure, placing it
   before the `cpumask_t affinity_mask` member. This is a safe change
   because:
   - It only reorders structure members
   - The RCU head doesn't need to be at any specific location
     functionally
   - Moving it earlier reduces the offset from the structure start
   - No functional code changes are required

4. **Affects Multiple Drivers**: The issue affects three Intel ethernet
   drivers (i40e, ixgbe, fm10k), all of which are fixed identically by
   moving the rcu member earlier in their respective q_vector
   structures.

5. **Configuration-Dependent Bug**: This bug only manifests with large
   CONFIG_NR_CPUS values (likely >= 512 or higher), where the
   `cpumask_t` type becomes large enough to push the rcu member beyond
   the 4096-byte offset limit. Systems with high core counts are
   becoming more common in production environments.

6. **No Risk of Regression**: The change is minimal and doesn't alter
   any functionality. It's purely a structural reordering that maintains
   all existing behavior while fixing the compilation issue.

7. **Meets Stable Criteria**: This fix clearly meets the stable kernel
   criteria as it:
   - Fixes a real bug (compilation failure)
   - Is minimal and contained
   - Has no risk of introducing new issues
   - Affects users with legitimate configurations

The commit is an excellent candidate for stable backporting as it fixes
a real compilation issue that prevents kernel builds on systems with
large CPU counts, and the fix is trivial with no risk of regression.

 drivers/net/ethernet/intel/fm10k/fm10k.h | 3 ++-
 drivers/net/ethernet/intel/i40e/i40e.h   | 2 +-
 drivers/net/ethernet/intel/ixgbe/ixgbe.h | 3 ++-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/fm10k/fm10k.h b/drivers/net/ethernet/intel/fm10k/fm10k.h
index 6119a41088381..65a2816142d96 100644
--- a/drivers/net/ethernet/intel/fm10k/fm10k.h
+++ b/drivers/net/ethernet/intel/fm10k/fm10k.h
@@ -189,13 +189,14 @@ struct fm10k_q_vector {
 	struct fm10k_ring_container rx, tx;
 
 	struct napi_struct napi;
+	struct rcu_head rcu;	/* to avoid race with update stats on free */
+
 	cpumask_t affinity_mask;
 	char name[IFNAMSIZ + 9];
 
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *dbg_q_vector;
 #endif /* CONFIG_DEBUG_FS */
-	struct rcu_head rcu;	/* to avoid race with update stats on free */
 
 	/* for dynamic allocation of rings associated with this q_vector */
 	struct fm10k_ring ring[] ____cacheline_internodealigned_in_smp;
diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index a143440f3db62..223d5831a5bbe 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -961,6 +961,7 @@ struct i40e_q_vector {
 	u16 reg_idx;		/* register index of the interrupt */
 
 	struct napi_struct napi;
+	struct rcu_head rcu;	/* to avoid race with update stats on free */
 
 	struct i40e_ring_container rx;
 	struct i40e_ring_container tx;
@@ -971,7 +972,6 @@ struct i40e_q_vector {
 	cpumask_t affinity_mask;
 	struct irq_affinity_notify affinity_notify;
 
-	struct rcu_head rcu;	/* to avoid race with update stats on free */
 	char name[I40E_INT_NAME_STR_LEN];
 	bool arm_wb_state;
 	bool in_busy_poll;
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index 737590a0d849e..09f7a3787f272 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -458,9 +458,10 @@ struct ixgbe_q_vector {
 	struct ixgbe_ring_container rx, tx;
 
 	struct napi_struct napi;
+	struct rcu_head rcu;	/* to avoid race with update stats on free */
+
 	cpumask_t affinity_mask;
 	int numa_node;
-	struct rcu_head rcu;	/* to avoid race with update stats on free */
 	char name[IFNAMSIZ + 9];
 
 	/* for dynamic allocation of rings associated with this q_vector */
-- 
2.39.5

[PATCH AUTOSEL 5.15 2/2] ASoC: Intel: fix SND_SOC_SOF dependencies

[Sasha Levin]

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit e837b59f8b411b5baf5e3de7a5aea10b1c545a63 ]

It is currently possible to configure a kernel with all Intel SoC
configs as loadable modules, but the board config as built-in. This
causes a link failure in the reference to the snd_soc_sof.ko module:

x86_64-linux-ld: sound/soc/intel/boards/sof_rt5682.o: in function `sof_rt5682_hw_params':
sof_rt5682.c:(.text+0x1f9): undefined reference to `sof_dai_get_mclk'
x86_64-linux-ld: sof_rt5682.c:(.text+0x234): undefined reference to `sof_dai_get_bclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_rt5682.o: in function `sof_rt5682_codec_init':
sof_rt5682.c:(.text+0x3e0): undefined reference to `sof_dai_get_mclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_cs42l42.o: in function `sof_cs42l42_hw_params':
sof_cs42l42.c:(.text+0x2a): undefined reference to `sof_dai_get_bclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_nau8825.o: in function `sof_nau8825_hw_params':
sof_nau8825.c:(.text+0x7f): undefined reference to `sof_dai_get_bclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_da7219.o: in function `da7219_codec_init':
sof_da7219.c:(.text+0xbf): undefined reference to `sof_dai_get_mclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_maxim_common.o: in function `max_98373_hw_params':
sof_maxim_common.c:(.text+0x6f9): undefined reference to `sof_dai_get_tdm_slots'
x86_64-linux-ld: sound/soc/intel/boards/sof_realtek_common.o: in function `rt1015_hw_params':
sof_realtek_common.c:(.text+0x54c): undefined reference to `sof_dai_get_bclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_realtek_common.o: in function `rt1308_hw_params':
sof_realtek_common.c:(.text+0x702): undefined reference to `sof_dai_get_mclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_cirrus_common.o: in function `cs35l41_hw_params':
sof_cirrus_common.c:(.text+0x2f): undefined reference to `sof_dai_get_bclk'

Add an optional dependency on SND_SOC_SOF_INTEL_COMMON, to ensure that whenever
the SOF support is in a loadable module, none of the board code can be built-in.

This may be be a little heavy-handed, but I also don't see a reason why one would
want the boards to be built-in but not the SoC, so it shouldn't actually cause
any usability problems.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20250709145626.64125-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

Based on my analysis of the commit and its context, here is my
assessment:

**YES** - This commit should be backported to stable kernel trees.

## Extensive Explanation:

### 1. **The commit fixes a critical build failure**
The commit addresses link errors that occur when Intel ASoC board
drivers are built-in (=y) while the SOF core module is built as a
loadable module (=m). The error messages show undefined references to
SOF DAI functions:
- `sof_dai_get_mclk`
- `sof_dai_get_bclk`
- `sof_dai_get_tdm_slots`

These functions are exported from the `snd-sof` module (defined in
`sound/soc/sof/sof-audio.c`), but when board drivers are built-in, they
cannot reference symbols from loadable modules.

### 2. **The fix is minimal and contained**
The change is a single-line modification to the Kconfig dependency:
```diff
-if SND_SOC_INTEL_MACH
+if SND_SOC_INTEL_MACH && (SND_SOC_SOF_INTEL_COMMON ||
!SND_SOC_SOF_INTEL_COMMON)
```

This clever dependency ensures that when `SND_SOC_SOF_INTEL_COMMON` is
built as a module (=m), the Intel machine drivers cannot be built-in
(=y). The `|| !SND_SOC_SOF_INTEL_COMMON` part allows the machine drivers
to be enabled when SOF support is completely disabled.

### 3. **Similar to previous backported fixes**
Looking at the historical commits:
- Commit `8d0872f6239f` (Similar Commit #1) fixed a similar link failure
  for `sof-nau8825` and was backported (YES)
- Commit `f4df4e4042b0` (Similar Commit #4) fixed a similar dependency
  issue with SOF IMX and was backported (YES)

Both of these commits addressed build/link failures caused by incorrect
Kconfig dependencies, just like this commit.

### 4. **No risk of regression**
The change only affects build configuration and doesn't modify any
runtime code. It prevents invalid configurations that would fail to
build anyway. As the commit message states: "it shouldn't actually cause
any usability problems" because there's no practical reason to have
board drivers built-in while the SOF core is a module.

### 5. **Meets stable tree criteria**
- Fixes a real bug (build failure)
- Small and contained change
- No new features or architectural changes
- Similar fixes have been backported before
- Low risk of introducing new issues

The commit follows the pattern of other Kconfig dependency fixes in the
Intel ASoC subsystem that have been successfully backported to stable
trees.

 sound/soc/intel/boards/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/intel/boards/Kconfig b/sound/soc/intel/boards/Kconfig
index 61b71d6c44cfa..960a1bd79489b 100644
--- a/sound/soc/intel/boards/Kconfig
+++ b/sound/soc/intel/boards/Kconfig
@@ -11,7 +11,7 @@ menuconfig SND_SOC_INTEL_MACH
 	 kernel: saying N will just cause the configurator to skip all
 	 the questions about Intel ASoC machine drivers.
 
-if SND_SOC_INTEL_MACH
+if SND_SOC_INTEL_MACH && (SND_SOC_SOF_INTEL_COMMON || !SND_SOC_SOF_INTEL_COMMON)
 
 config SND_SOC_INTEL_USER_FRIENDLY_LONG_NAMES
 	bool "Use more user friendly long card names"
-- 
2.39.5