[PATCH net V4 0/4] net/mlx5: Fixes for Socket-Direct

[PATCH net V4 0/4] net/mlx5: Fixes for Socket-Direct

[Tariq Toukan]

Hi,

This series fixes several race conditions and bugs in the mlx5
Socket-Direct (SD) single netdev flow.

Patch 1 serializes mlx5_sd_init()/mlx5_sd_cleanup() with
mlx5_devcom_comp_lock() and tracks the SD group state on the primary
device, preventing concurrent or duplicate bring-up/tear-down.

Patch 2 fixes the debugfs "multi-pf" directory being stored on the
calling device's sd struct instead of the primary's, which caused
memory leaks and recreation errors when cleanup ran from a different PF.

Patch 3 fixes a race where a secondary PF could access the primary's
auxiliary device after it had been unbound, by holding the primary's
device lock while operating on its auxiliary device.

Patch 4 fixes missing cleanup on ETH probe errors. The analogous gap on
the resume path requires introducing sd_suspend/resume APIs that only
destroy FW resources and is left for a follow-up series.

Regards,
Tariq

V4:
- Link to V3:
  https://lore.kernel.org/all/20260423123104.201552-1-tariqt@nvidia.com/
- Adjust "net/mlx5e: SD, Fix missing cleanup on probe/resume error" to
  cleanup SD only on probe; the resume gap is deferred to a follow-up
  series that will introduce sd_suspend/resume APIs.
- Fix concurrent cleanup vs. init race in
  "net/mlx5: SD: Serialize init/cleanup".
- Remove leftover sentence in commit message of
  "net/mlx5: SD: Serialize init/cleanup"

Shay Drory (4):
  net/mlx5: SD: Serialize init/cleanup
  net/mlx5: SD, Keep multi-pf debugfs entries on primary
  net/mlx5e: SD, Fix missing cleanup on probe error
  net/mlx5e: SD, Fix race condition in secondary device probe/remove

 .../net/ethernet/mellanox/mlx5/core/en_main.c | 26 +++++--
 .../net/ethernet/mellanox/mlx5/core/lib/sd.c  | 76 ++++++++++++++++---
 .../net/ethernet/mellanox/mlx5/core/lib/sd.h  |  2 +
 3 files changed, 87 insertions(+), 17 deletions(-)


base-commit: 3bc179bc7146c26c9dff75d2943d10528274e301
-- 
2.44.0

[PATCH net V4 1/4] net/mlx5: SD: Serialize init/cleanup

[Tariq Toukan]

From: Shay Drory <shayd@nvidia.com>

mlx5_sd_init() / mlx5_sd_cleanup() may run from multiple PFs in the same
Socket-Direct group. This can cause the SD bring-up/tear-down sequence
to be executed more than once or interleaved across PFs.

Protect SD init/cleanup with mlx5_devcom_comp_lock() and track the SD
group state on the primary device. Skip init if the primary is already
UP, and skip cleanup unless the primary is UP.

The state check on cleanup is needed because sd_register() drops the
devcom comp lock between marking the comp ready and assigning
primary_dev on each peer. A concurrent cleanup that acquires the lock
in this window would observe devcom_is_ready==true while primary_dev
is still NULL (causing mlx5_sd_get_primary() to return NULL) or while
the FW alias setup performed by mlx5_sd_init()'s body has not yet run
(causing sd_cmd_unset_primary() to dereference a NULL tx_ft). Gate the
cleanup body on primary_sd->state == MLX5_SD_STATE_UP, which is set
only at the very end of mlx5_sd_init() under the same comp lock - so
observing UP guarantees primary_dev, secondaries[], tx_ft, and dfs are
all populated. Also bail explicitly if mlx5_sd_get_primary() returns
NULL, in case state is checked on a peer whose primary_dev hasn't been
assigned yet.

In addition, move mlx5_devcom_comp_set_ready(false) from sd_unregister()
into the cleanup's locked section. A concurrent init acquiring the
devcom lock will now observe devcom is no longer ready and bail out
immediately.

Fixes: 381978d28317 ("net/mlx5e: Create single netdev per SD group")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../net/ethernet/mellanox/mlx5/core/lib/sd.c  | 40 ++++++++++++++++---
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
index 762c783156b4..d42c283cbb38 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
@@ -18,6 +18,7 @@ struct mlx5_sd {
 	u8 host_buses;
 	struct mlx5_devcom_comp_dev *devcom;
 	struct dentry *dfs;
+	u8 state;
 	bool primary;
 	union {
 		struct { /* primary */
@@ -31,6 +32,11 @@ struct mlx5_sd {
 	};
 };
 
+enum mlx5_sd_state {
+	MLX5_SD_STATE_DOWN = 0,
+	MLX5_SD_STATE_UP,
+};
+
 static int mlx5_sd_get_host_buses(struct mlx5_core_dev *dev)
 {
 	struct mlx5_sd *sd = mlx5_get_sd(dev);
@@ -270,9 +276,6 @@ static void sd_unregister(struct mlx5_core_dev *dev)
 {
 	struct mlx5_sd *sd = mlx5_get_sd(dev);
 
-	mlx5_devcom_comp_lock(sd->devcom);
-	mlx5_devcom_comp_set_ready(sd->devcom, false);
-	mlx5_devcom_comp_unlock(sd->devcom);
 	mlx5_devcom_unregister_component(sd->devcom);
 }
 
@@ -426,6 +429,7 @@ int mlx5_sd_init(struct mlx5_core_dev *dev)
 	struct mlx5_core_dev *primary, *pos, *to;
 	struct mlx5_sd *sd = mlx5_get_sd(dev);
 	u8 alias_key[ACCESS_KEY_LEN];
+	struct mlx5_sd *primary_sd;
 	int err, i;
 
 	err = sd_init(dev);
@@ -440,10 +444,17 @@ int mlx5_sd_init(struct mlx5_core_dev *dev)
 	if (err)
 		goto err_sd_cleanup;
 
+	mlx5_devcom_comp_lock(sd->devcom);
 	if (!mlx5_devcom_comp_is_ready(sd->devcom))
-		return 0;
+		goto out;
 
 	primary = mlx5_sd_get_primary(dev);
+	if (!primary)
+		goto out;
+
+	primary_sd = mlx5_get_sd(primary);
+	if (primary_sd->state != MLX5_SD_STATE_DOWN)
+		goto out;
 
 	for (i = 0; i < ACCESS_KEY_LEN; i++)
 		alias_key[i] = get_random_u8();
@@ -472,6 +483,9 @@ int mlx5_sd_init(struct mlx5_core_dev *dev)
 		sd->group_id, mlx5_devcom_comp_get_size(sd->devcom));
 	sd_print_group(primary);
 
+	primary_sd->state = MLX5_SD_STATE_UP;
+out:
+	mlx5_devcom_comp_unlock(sd->devcom);
 	return 0;
 
 err_unset_secondaries:
@@ -481,6 +495,8 @@ int mlx5_sd_init(struct mlx5_core_dev *dev)
 	sd_cmd_unset_primary(primary);
 	debugfs_remove_recursive(sd->dfs);
 err_sd_unregister:
+	mlx5_devcom_comp_set_ready(sd->devcom, false);
+	mlx5_devcom_comp_unlock(sd->devcom);
 	sd_unregister(dev);
 err_sd_cleanup:
 	sd_cleanup(dev);
@@ -491,22 +507,34 @@ void mlx5_sd_cleanup(struct mlx5_core_dev *dev)
 {
 	struct mlx5_sd *sd = mlx5_get_sd(dev);
 	struct mlx5_core_dev *primary, *pos;
+	struct mlx5_sd *primary_sd;
 	int i;
 
 	if (!sd)
 		return;
 
+	mlx5_devcom_comp_lock(sd->devcom);
 	if (!mlx5_devcom_comp_is_ready(sd->devcom))
-		goto out;
+		goto out_unlock;
 
 	primary = mlx5_sd_get_primary(dev);
+	if (!primary)
+		goto out_unlock;
+
+	primary_sd = mlx5_get_sd(primary);
+	if (primary_sd->state != MLX5_SD_STATE_UP)
+		goto out_unlock;
+
 	mlx5_sd_for_each_secondary(i, primary, pos)
 		sd_cmd_unset_secondary(pos);
 	sd_cmd_unset_primary(primary);
 	debugfs_remove_recursive(sd->dfs);
 
 	sd_info(primary, "group id %#x, uncombined\n", sd->group_id);
-out:
+	primary_sd->state = MLX5_SD_STATE_DOWN;
+	mlx5_devcom_comp_set_ready(sd->devcom, false);
+out_unlock:
+	mlx5_devcom_comp_unlock(sd->devcom);
 	sd_unregister(dev);
 	sd_cleanup(dev);
 }
-- 
2.44.0

[PATCH net V4 2/4] net/mlx5: SD, Keep multi-pf debugfs entries on primary

[Tariq Toukan]

From: Shay Drory <shayd@nvidia.com>

mlx5_sd_init() creates the "multi-pf" debugfs directory under the
primary device debugfs root, but stored the dentry in the calling
device's sd struct. When sd_cleanup() run on a different PF,
this leads to using the wrong sd->dfs for removing entries, which
results in memory leak and an error in when re-creating the SD.[1]

Fix it by explicitly storing the debugfs dentry in the primary
device sd struct and use it for all per-group files.

[1]
debugfs: 'multi-pf' already exists in '0000:08:00.1'

Fixes: 4375130bf527 ("net/mlx5: SD, Add debugfs")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../net/ethernet/mellanox/mlx5/core/lib/sd.c  | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
index d42c283cbb38..7a1787f15320 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
@@ -463,9 +463,13 @@ int mlx5_sd_init(struct mlx5_core_dev *dev)
 	if (err)
 		goto err_sd_unregister;
 
-	sd->dfs = debugfs_create_dir("multi-pf", mlx5_debugfs_get_dev_root(primary));
-	debugfs_create_x32("group_id", 0400, sd->dfs, &sd->group_id);
-	debugfs_create_file("primary", 0400, sd->dfs, primary, &dev_fops);
+	primary_sd->dfs =
+		debugfs_create_dir("multi-pf",
+				   mlx5_debugfs_get_dev_root(primary));
+	debugfs_create_x32("group_id", 0400, primary_sd->dfs,
+			   &primary_sd->group_id);
+	debugfs_create_file("primary", 0400, primary_sd->dfs, primary,
+			    &dev_fops);
 
 	mlx5_sd_for_each_secondary(i, primary, pos) {
 		char name[32];
@@ -475,7 +479,8 @@ int mlx5_sd_init(struct mlx5_core_dev *dev)
 			goto err_unset_secondaries;
 
 		snprintf(name, sizeof(name), "secondary_%d", i - 1);
-		debugfs_create_file(name, 0400, sd->dfs, pos, &dev_fops);
+		debugfs_create_file(name, 0400, primary_sd->dfs, pos,
+				    &dev_fops);
 
 	}
 
@@ -493,7 +498,8 @@ int mlx5_sd_init(struct mlx5_core_dev *dev)
 	mlx5_sd_for_each_secondary_to(i, primary, to, pos)
 		sd_cmd_unset_secondary(pos);
 	sd_cmd_unset_primary(primary);
-	debugfs_remove_recursive(sd->dfs);
+	debugfs_remove_recursive(primary_sd->dfs);
+	primary_sd->dfs = NULL;
 err_sd_unregister:
 	mlx5_devcom_comp_set_ready(sd->devcom, false);
 	mlx5_devcom_comp_unlock(sd->devcom);
@@ -528,7 +534,8 @@ void mlx5_sd_cleanup(struct mlx5_core_dev *dev)
 	mlx5_sd_for_each_secondary(i, primary, pos)
 		sd_cmd_unset_secondary(pos);
 	sd_cmd_unset_primary(primary);
-	debugfs_remove_recursive(sd->dfs);
+	debugfs_remove_recursive(primary_sd->dfs);
+	primary_sd->dfs = NULL;
 
 	sd_info(primary, "group id %#x, uncombined\n", sd->group_id);
 	primary_sd->state = MLX5_SD_STATE_DOWN;
-- 
2.44.0

[PATCH net V4 3/4] net/mlx5e: SD, Fix missing cleanup on probe error

[Tariq Toukan]

From: Shay Drory <shayd@nvidia.com>

When _mlx5e_probe() fails, the preceding successful mlx5_sd_init() is
not undone. Auxiliary bus probe failure skips binding, so mlx5e_remove()
is never called for that adev and the matching mlx5_sd_cleanup() never
runs - leaking the per-dev SD struct.

Call mlx5_sd_cleanup() on the probe error path to balance
mlx5_sd_init().

A similar gap exists on the resume path: mlx5_sd_init() and
mlx5_sd_cleanup() are currently bundled with both probe/remove and
suspend/resume, even though only the FW alias state actually needs to
follow the suspend/resume lifecycle - the sd struct allocation and
devcom membership are software state that should track the full bound
lifetime. As a result, a failed resume can leave a still-bound device
with sd == NULL, which mlx5_sd_get_adev() can't distinguish from a
non-SD device. Fixing this requires sd_suspend/resume APIs which will
only destroy FW resources and is left for a follow-up series.

Fixes: 381978d28317 ("net/mlx5e: Create single netdev per SD group")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 5a46870c4b74..e21affd0ffc4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -6775,8 +6775,8 @@ static int mlx5e_resume(struct auxiliary_device *adev)
 
 	actual_adev = mlx5_sd_get_adev(mdev, adev, edev->idx);
 	if (actual_adev)
-		return _mlx5e_resume(actual_adev);
-	return 0;
+		err = _mlx5e_resume(actual_adev);
+	return err;
 }
 
 static int _mlx5e_suspend(struct auxiliary_device *adev, bool pre_netdev_reg)
@@ -6912,9 +6912,16 @@ static int mlx5e_probe(struct auxiliary_device *adev,
 		return err;
 
 	actual_adev = mlx5_sd_get_adev(mdev, adev, edev->idx);
-	if (actual_adev)
-		return _mlx5e_probe(actual_adev);
+	if (actual_adev) {
+		err = _mlx5e_probe(actual_adev);
+		if (err)
+			goto sd_cleanup;
+	}
 	return 0;
+
+sd_cleanup:
+	mlx5_sd_cleanup(mdev);
+	return err;
 }
 
 static void _mlx5e_remove(struct auxiliary_device *adev)
-- 
2.44.0

[PATCH net V4 4/4] net/mlx5e: SD, Fix race condition in secondary device probe/remove

[Tariq Toukan]

From: Shay Drory <shayd@nvidia.com>

When utilizing Socket-Direct single netdev functionality the driver
resolves the actual auxiliary device using mlx5_sd_get_adev(). However,
the current implementation returns the primary ETH auxiliary device
without holding the device lock, leading to a potential race condition
where the ETH device could be unbound or removed concurrently during
probe, suspend, resume, or remove operations.[1]

Fix this by introducing mlx5_sd_put_adev() and updating
mlx5_sd_get_adev() so that secondaries devices would acquire the device
lock of the returned auxiliary device. After the lock is acquired, a
second devcom check is needed[2].
In addition, update The callers to pair the get operation with the new
put operation, ensuring the lock is held while the auxiliary device is
being operated on and released afterwards.

The "primary" designation is determined once in sd_register(). It's set
before devcom is marked ready, and it never changes after that.
In Addition, The primary path never locks a secondary: When the primary
device invoke mlx5_sd_get_adev(), it sees dev == primary and returns.
no additional lock is taken.
Therefore lock ordering is always: secondary_lock -> primary_lock. The
reverse never happens, so ABBA deadlock is impossible.

[1]
for example:
BUG: kernel NULL pointer dereference, address: 0000000000000370
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP
CPU: 4 UID: 0 PID: 3945 Comm: bash Not tainted 6.19.0-rc3+ #1 NONE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:mlx5e_dcbnl_dscp_app+0x23/0x100 [mlx5_core]
Call Trace:
 <TASK>
 mlx5e_remove+0x82/0x12a [mlx5_core]
 device_release_driver_internal+0x194/0x1f0
 bus_remove_device+0xc6/0x140
 device_del+0x159/0x3c0
 ? devl_param_driverinit_value_get+0x29/0x80
 mlx5_rescan_drivers_locked+0x92/0x160 [mlx5_core]
 mlx5_unregister_device+0x34/0x50 [mlx5_core]
 mlx5_uninit_one+0x43/0xb0 [mlx5_core]
 remove_one+0x4e/0xc0 [mlx5_core]
 pci_device_remove+0x39/0xa0
 device_release_driver_internal+0x194/0x1f0
 unbind_store+0x99/0xa0
 kernfs_fop_write_iter+0x12e/0x1e0
 vfs_write+0x215/0x3d0
 ksys_write+0x5f/0xd0
 do_syscall_64+0x55/0xe90
 entry_SYSCALL_64_after_hwframe+0x4b/0x53

[2]
    CPU0 (primary)                     CPU1 (secondary)
==========================================================================
mlx5e_remove() (device_lock held)
                                     mlx5e_remove() (2nd device_lock held)
                                      mlx5_sd_get_adev()
                                       mlx5_devcom_comp_is_ready() => true
                                       device_lock(primary)
 mlx5_sd_get_adev() ==> ret adev
 _mlx5e_remove()
 mlx5_sd_cleanup()
 // mlx5e_remove finished
 // releasing device_lock
                                       //need another check here...
                                       mlx5_devcom_comp_is_ready() => false

Fixes: 381978d28317 ("net/mlx5e: Create single netdev per SD group")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../net/ethernet/mellanox/mlx5/core/en_main.c   | 11 ++++++++++-
 .../net/ethernet/mellanox/mlx5/core/lib/sd.c    | 17 +++++++++++++++++
 .../net/ethernet/mellanox/mlx5/core/lib/sd.h    |  2 ++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index e21affd0ffc4..b09806dfebe5 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -6774,8 +6774,10 @@ static int mlx5e_resume(struct auxiliary_device *adev)
 		return err;
 
 	actual_adev = mlx5_sd_get_adev(mdev, adev, edev->idx);
-	if (actual_adev)
+	if (actual_adev) {
 		err = _mlx5e_resume(actual_adev);
+		mlx5_sd_put_adev(actual_adev, adev);
+	}
 	return err;
 }
 
@@ -6815,6 +6817,8 @@ static int mlx5e_suspend(struct auxiliary_device *adev, pm_message_t state)
 		err = _mlx5e_suspend(actual_adev, false);
 
 	mlx5_sd_cleanup(mdev);
+	if (actual_adev)
+		mlx5_sd_put_adev(actual_adev, adev);
 	return err;
 }
 
@@ -6916,11 +6920,14 @@ static int mlx5e_probe(struct auxiliary_device *adev,
 		err = _mlx5e_probe(actual_adev);
 		if (err)
 			goto sd_cleanup;
+		mlx5_sd_put_adev(actual_adev, adev);
 	}
 	return 0;
 
 sd_cleanup:
 	mlx5_sd_cleanup(mdev);
+	if (actual_adev)
+		mlx5_sd_put_adev(actual_adev, adev);
 	return err;
 }
 
@@ -6973,6 +6980,8 @@ static void mlx5e_remove(struct auxiliary_device *adev)
 		_mlx5e_remove(actual_adev);
 
 	mlx5_sd_cleanup(mdev);
+	if (actual_adev)
+		mlx5_sd_put_adev(actual_adev, adev);
 }
 
 static const struct auxiliary_device_id mlx5e_id_table[] = {
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
index 7a1787f15320..a43ae482a679 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c
@@ -546,6 +546,10 @@ void mlx5_sd_cleanup(struct mlx5_core_dev *dev)
 	sd_cleanup(dev);
 }
 
+/* Cannot take devcom lock as a gate for device lock. ABBA deadlock:
+ * primary:  actual_adev_lock -> SD devcom comp lock
+ * secondary: SD devcom comp lock -> actual_adev_lock
+ */
 struct auxiliary_device *mlx5_sd_get_adev(struct mlx5_core_dev *dev,
 					  struct auxiliary_device *adev,
 					  int idx)
@@ -563,5 +567,18 @@ struct auxiliary_device *mlx5_sd_get_adev(struct mlx5_core_dev *dev,
 	if (dev == primary)
 		return adev;
 
+	device_lock(&primary->priv.adev[idx]->adev.dev);
+	/* In case primary finish removing its adev */
+	if (!mlx5_devcom_comp_is_ready(sd->devcom)) {
+		device_unlock(&primary->priv.adev[idx]->adev.dev);
+		return NULL;
+	}
 	return &primary->priv.adev[idx]->adev;
 }
+
+void mlx5_sd_put_adev(struct auxiliary_device *actual_adev,
+		      struct auxiliary_device *adev)
+{
+	if (actual_adev != adev)
+		device_unlock(&actual_adev->dev);
+}
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.h b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.h
index 137efaf9aabc..9bfd5b9756b5 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/sd.h
@@ -15,6 +15,8 @@ struct mlx5_core_dev *mlx5_sd_ch_ix_get_dev(struct mlx5_core_dev *primary, int c
 struct auxiliary_device *mlx5_sd_get_adev(struct mlx5_core_dev *dev,
 					  struct auxiliary_device *adev,
 					  int idx);
+void mlx5_sd_put_adev(struct auxiliary_device *actual_adev,
+		      struct auxiliary_device *adev);
 
 int mlx5_sd_init(struct mlx5_core_dev *dev);
 void mlx5_sd_cleanup(struct mlx5_core_dev *dev);
-- 
2.44.0