diff mbox series

[net-next,1/5] gve: Add adminq mutex lock

Message ID 20240507225945.1408516-2-ziweixiao@google.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series gve: Add flow steering support | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 926 this patch: 926
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 10 of 10 maintainers
netdev/build_clang success Errors and warnings before: 940 this patch: 940
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 937 this patch: 937
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 53 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Ziwei Xiao May 7, 2024, 10:59 p.m. UTC 
We were depending on the rtnl_lock to make sure there is only one adminq
command running at a time. But some commands may take too long to hold
the rtnl_lock, such as the upcoming flow steering operations. For such
situations, it can temporarily drop the rtnl_lock, and replace it for
these operations with a new adminq lock, which can ensure the adminq
command execution to be thread-safe.

Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
---
 drivers/net/ethernet/google/gve/gve.h        |  1 +
 drivers/net/ethernet/google/gve/gve_adminq.c | 22 +++++++++++---------
 2 files changed, 13 insertions(+), 10 deletions(-)

Comments

Markus Elfring May 8, 2024, 12:07 p.m. UTC | #1 
…
> the rtnl_lock, such as the upcoming flow steering operations. For such
> situations, it can temporarily drop the rtnl_lock, and replace it for
> these operations with a new adminq lock, which can ensure the adminq
> command execution to be thread-safe.

Would you like to use imperative wordings for an improved change description?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.9-rc7#n94

Regards,
Markus
diff mbox series

Patch

diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index ae1e21c9b0a5..ca7fce17f2c0 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -724,6 +724,7 @@  struct gve_priv {
 	union gve_adminq_command *adminq;
 	dma_addr_t adminq_bus_addr;
 	struct dma_pool *adminq_pool;
+	struct mutex adminq_lock; /* Protects adminq command execution */
 	u32 adminq_mask; /* masks prod_cnt to adminq size */
 	u32 adminq_prod_cnt; /* free-running count of AQ cmds executed */
 	u32 adminq_cmd_fail; /* free-running count of AQ cmds failed */
diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
index 3df8243680d9..2c3ec5c3b114 100644
--- a/drivers/net/ethernet/google/gve/gve_adminq.c
+++ b/drivers/net/ethernet/google/gve/gve_adminq.c
@@ -284,6 +284,7 @@  int gve_adminq_alloc(struct device *dev, struct gve_priv *priv)
 			    &priv->reg_bar0->adminq_base_address_lo);
 		iowrite32be(GVE_DRIVER_STATUS_RUN_MASK, &priv->reg_bar0->driver_status);
 	}
+	mutex_init(&priv->adminq_lock);
 	gve_set_admin_queue_ok(priv);
 	return 0;
 }
@@ -511,28 +512,29 @@  static int gve_adminq_issue_cmd(struct gve_priv *priv,
 	return 0;
 }
 
-/* This function is not threadsafe - the caller is responsible for any
- * necessary locks.
- * The caller is also responsible for making sure there are no commands
- * waiting to be executed.
- */
 static int gve_adminq_execute_cmd(struct gve_priv *priv,
 				  union gve_adminq_command *cmd_orig)
 {
 	u32 tail, head;
 	int err;
 
+	mutex_lock(&priv->adminq_lock);
 	tail = ioread32be(&priv->reg_bar0->adminq_event_counter);
 	head = priv->adminq_prod_cnt;
-	if (tail != head)
-		// This is not a valid path
-		return -EINVAL;
+	if (tail != head) {
+		err = -EINVAL;
+		goto out;
+	}
 
 	err = gve_adminq_issue_cmd(priv, cmd_orig);
 	if (err)
-		return err;
+		goto out;
 
-	return gve_adminq_kick_and_wait(priv);
+	err = gve_adminq_kick_and_wait(priv);
+
+out:
+	mutex_unlock(&priv->adminq_lock);
+	return err;
 }
 
 /* The device specifies that the management vector can either be the first irq