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 b14441944b4b2..db72e5e4acd36 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[0] ____cacheline_internodealigned_in_smp; diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h index 4c8c31692e9e0..edb5e408c980f 100644 --- a/drivers/net/ethernet/intel/i40e/i40e.h +++ b/drivers/net/ethernet/intel/i40e/i40e.h @@ -864,6 +864,7 @@ 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; @@ -874,7 +875,6 @@ 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; } ____cacheline_internodealigned_in_smp; diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h index 0142ca226bf50..0f9a1fce0dee9 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 */
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 5c27f7ab4a5f5..78a75c29ed88f 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)
if SND_SOC_INTEL_HASWELL
linux-stable-mirror@lists.linaro.org
-
Sasha Levin