[PATCH v4 net 0/4] pds_core: updates and fixes

[PATCH v4 net 0/4] pds_core: updates and fixes

[Shannon Nelson]

This patchset has fixes for issues seen in recent internal testing
of error conditions and stress handling.

Note that the first patch in this series is a leftover from an
earlier patchset that was abandoned:
Link: https://lore.kernel.org/netdev/20250129004337.36898-2-shannon.nelson@amd.com/

v4:
 - use init/reinit_completion() rather than COMPLETION_INITIALIZER_ONSTACK()
 - use completion_done() to protect from completing timed-out requests

v3:
https://lore.kernel.org/netdev/20250415232931.59693-1-shannon.nelson@amd.com/
 - dropped the kdoc complaint fix, save for later net-next update

v2:
https://lore.kernel.org/netdev/20250411003209.44053-1-shannon.nelson@amd.com/
 - dropped patch 5/6 "adminq poll interval", will send for net-next later
 - updated commit comments and tags

v1:
https://lore.kernel.org/netdev/20250407225113.51850-1-shannon.nelson@amd.com/

Brett Creeley (3):
  pds_core: Prevent possible adminq overflow/stuck condition
  pds_core: handle unsupported PDS_CORE_CMD_FW_CONTROL result
  pds_core: Remove unnecessary check in pds_client_adminq_cmd()

Shannon Nelson (1):
  pds_core: make wait_context part of q_info

 drivers/net/ethernet/amd/pds_core/adminq.c  | 36 ++++++++-------------
 drivers/net/ethernet/amd/pds_core/auxbus.c  |  3 --
 drivers/net/ethernet/amd/pds_core/core.c    |  9 +++---
 drivers/net/ethernet/amd/pds_core/core.h    |  4 +--
 drivers/net/ethernet/amd/pds_core/devlink.c |  4 +--
 5 files changed, 21 insertions(+), 35 deletions(-)

-- 
2.17.1

[PATCH v4 net 1/4] pds_core: Prevent possible adminq overflow/stuck condition

[Shannon Nelson]

From: Brett Creeley <brett.creeley@amd.com>

The pds_core's adminq is protected by the adminq_lock, which prevents
more than 1 command to be posted onto it at any one time. This makes it
so the client drivers cannot simultaneously post adminq commands.
However, the completions happen in a different context, which means
multiple adminq commands can be posted sequentially and all waiting
on completion.

On the FW side, the backing adminq request queue is only 16 entries
long and the retry mechanism and/or overflow/stuck prevention is
lacking. This can cause the adminq to get stuck, so commands are no
longer processed and completions are no longer sent by the FW.

As an initial fix, prevent more than 16 outstanding adminq commands so
there's no way to cause the adminq from getting stuck. This works
because the backing adminq request queue will never have more than 16
pending adminq commands, so it will never overflow. This is done by
reducing the adminq depth to 16.

Fixes: 45d76f492938 ("pds_core: set up device and adminq")
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
---
 drivers/net/ethernet/amd/pds_core/core.c | 5 +----
 drivers/net/ethernet/amd/pds_core/core.h | 2 +-
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/amd/pds_core/core.c b/drivers/net/ethernet/amd/pds_core/core.c
index 1eb0d92786f7..55163457f12b 100644
--- a/drivers/net/ethernet/amd/pds_core/core.c
+++ b/drivers/net/ethernet/amd/pds_core/core.c
@@ -325,10 +325,7 @@ static int pdsc_core_init(struct pdsc *pdsc)
 	size_t sz;
 	int err;
 
-	/* Scale the descriptor ring length based on number of CPUs and VFs */
-	numdescs = max_t(int, PDSC_ADMINQ_MIN_LENGTH, num_online_cpus());
-	numdescs += 2 * pci_sriov_get_totalvfs(pdsc->pdev);
-	numdescs = roundup_pow_of_two(numdescs);
+	numdescs = PDSC_ADMINQ_MAX_LENGTH;
 	err = pdsc_qcq_alloc(pdsc, PDS_CORE_QTYPE_ADMINQ, 0, "adminq",
 			     PDS_CORE_QCQ_F_CORE | PDS_CORE_QCQ_F_INTR,
 			     numdescs,
diff --git a/drivers/net/ethernet/amd/pds_core/core.h b/drivers/net/ethernet/amd/pds_core/core.h
index 0bf320c43083..199473112c29 100644
--- a/drivers/net/ethernet/amd/pds_core/core.h
+++ b/drivers/net/ethernet/amd/pds_core/core.h
@@ -16,7 +16,7 @@
 
 #define PDSC_WATCHDOG_SECS	5
 #define PDSC_QUEUE_NAME_MAX_SZ  16
-#define PDSC_ADMINQ_MIN_LENGTH	16	/* must be a power of two */
+#define PDSC_ADMINQ_MAX_LENGTH	16	/* must be a power of two */
 #define PDSC_NOTIFYQ_LENGTH	64	/* must be a power of two */
 #define PDSC_TEARDOWN_RECOVERY	false
 #define PDSC_TEARDOWN_REMOVING	true
-- 
2.17.1

[PATCH v4 net 2/4] pds_core: handle unsupported PDS_CORE_CMD_FW_CONTROL result

[Shannon Nelson]

From: Brett Creeley <brett.creeley@amd.com>

If the FW doesn't support the PDS_CORE_CMD_FW_CONTROL command
the driver might at the least print garbage and at the worst
crash when the user runs the "devlink dev info" devlink command.

This happens because the stack variable fw_list is not 0
initialized which results in fw_list.num_fw_slots being a
garbage value from the stack.  Then the driver tries to access
fw_list.fw_names[i] with i >= ARRAY_SIZE and runs off the end
of the array.

Fix this by initializing the fw_list and by not failing
completely if the devcmd fails because other useful information
is printed via devlink dev info even if the devcmd fails.

Fixes: 45d76f492938 ("pds_core: set up device and adminq")
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
---
 drivers/net/ethernet/amd/pds_core/devlink.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/amd/pds_core/devlink.c b/drivers/net/ethernet/amd/pds_core/devlink.c
index c5c787df61a4..d8dc39da4161 100644
--- a/drivers/net/ethernet/amd/pds_core/devlink.c
+++ b/drivers/net/ethernet/amd/pds_core/devlink.c
@@ -105,7 +105,7 @@ int pdsc_dl_info_get(struct devlink *dl, struct devlink_info_req *req,
 		.fw_control.opcode = PDS_CORE_CMD_FW_CONTROL,
 		.fw_control.oper = PDS_CORE_FW_GET_LIST,
 	};
-	struct pds_core_fw_list_info fw_list;
+	struct pds_core_fw_list_info fw_list = {};
 	struct pdsc *pdsc = devlink_priv(dl);
 	union pds_core_dev_comp comp;
 	char buf[32];
@@ -118,8 +118,6 @@ int pdsc_dl_info_get(struct devlink *dl, struct devlink_info_req *req,
 	if (!err)
 		memcpy_fromio(&fw_list, pdsc->cmd_regs->data, sizeof(fw_list));
 	mutex_unlock(&pdsc->devcmd_lock);
-	if (err && err != -EIO)
-		return err;
 
 	listlen = min(fw_list.num_fw_slots, ARRAY_SIZE(fw_list.fw_names));
 	for (i = 0; i < listlen; i++) {
-- 
2.17.1

[PATCH v4 net 3/4] pds_core: Remove unnecessary check in pds_client_adminq_cmd()

[Shannon Nelson]

From: Brett Creeley <brett.creeley@amd.com>

When the pds_core driver was first created there were some race
conditions around using the adminq, especially for client drivers.
To reduce the possibility of a race condition there's a check
against pf->state in pds_client_adminq_cmd(). This is problematic
for a couple of reasons:

1. The PDSC_S_INITING_DRIVER bit is set during probe, but not
   cleared until after everything in probe is complete, which
   includes creating the auxiliary devices. For pds_fwctl this
   means it can't make any adminq commands until after pds_core's
   probe is complete even though the adminq is fully up by the
   time pds_fwctl's auxiliary device is created.

2. The race conditions around using the adminq have been fixed
   and this path is already protected against client drivers
   calling pds_client_adminq_cmd() if the adminq isn't ready,
   i.e. see pdsc_adminq_post() -> pdsc_adminq_inc_if_up().

Fix this by removing the pf->state check in pds_client_adminq_cmd()
because invalid accesses to pds_core's adminq is already handled by
pdsc_adminq_post()->pdsc_adminq_inc_if_up().

Fixes: 10659034c622 ("pds_core: add the aux client API")
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
---
 drivers/net/ethernet/amd/pds_core/auxbus.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/ethernet/amd/pds_core/auxbus.c b/drivers/net/ethernet/amd/pds_core/auxbus.c
index eeb72b1809ea..c9aac27883a3 100644
--- a/drivers/net/ethernet/amd/pds_core/auxbus.c
+++ b/drivers/net/ethernet/amd/pds_core/auxbus.c
@@ -107,9 +107,6 @@ int pds_client_adminq_cmd(struct pds_auxiliary_dev *padev,
 	dev_dbg(pf->dev, "%s: %s opcode %d\n",
 		__func__, dev_name(&padev->aux_dev.dev), req->opcode);
 
-	if (pf->state)
-		return -ENXIO;
-
 	/* Wrap the client's request */
 	cmd.client_request.opcode = PDS_AQ_CMD_CLIENT_CMD;
 	cmd.client_request.client_id = cpu_to_le16(padev->client_id);
-- 
2.17.1

[PATCH v4 net 4/4] pds_core: make wait_context part of q_info

[Shannon Nelson]

Make the wait_context a full part of the q_info struct rather
than a stack variable that goes away after pdsc_adminq_post()
is done so that the context is still available after the wait
loop has given up.

There was a case where a slow development firmware caused
the adminq request to time out, but then later the FW finally
finished the request and sent the interrupt.  The handler tried
to complete_all() the completion context that had been created
on the stack in pdsc_adminq_post() but no longer existed.
This caused bad pointer usage, kernel crashes, and much wailing
and gnashing of teeth.

Fixes: 01ba61b55b20 ("pds_core: Add adminq processing and commands")
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
---
 drivers/net/ethernet/amd/pds_core/adminq.c | 36 +++++++++-------------
 drivers/net/ethernet/amd/pds_core/core.c   |  4 ++-
 drivers/net/ethernet/amd/pds_core/core.h   |  2 +-
 3 files changed, 18 insertions(+), 24 deletions(-)

diff --git a/drivers/net/ethernet/amd/pds_core/adminq.c b/drivers/net/ethernet/amd/pds_core/adminq.c
index c83a0a80d533..506f682d15c1 100644
--- a/drivers/net/ethernet/amd/pds_core/adminq.c
+++ b/drivers/net/ethernet/amd/pds_core/adminq.c
@@ -5,11 +5,6 @@
 
 #include "core.h"
 
-struct pdsc_wait_context {
-	struct pdsc_qcq *qcq;
-	struct completion wait_completion;
-};
-
 static int pdsc_process_notifyq(struct pdsc_qcq *qcq)
 {
 	union pds_core_notifyq_comp *comp;
@@ -109,10 +104,10 @@ void pdsc_process_adminq(struct pdsc_qcq *qcq)
 		q_info = &q->info[q->tail_idx];
 		q->tail_idx = (q->tail_idx + 1) & (q->num_descs - 1);
 
-		/* Copy out the completion data */
-		memcpy(q_info->dest, comp, sizeof(*comp));
-
-		complete_all(&q_info->wc->wait_completion);
+		if (!completion_done(&q_info->completion)) {
+			memcpy(q_info->dest, comp, sizeof(*comp));
+			complete(&q_info->completion);
+		}
 
 		if (cq->tail_idx == cq->num_descs - 1)
 			cq->done_color = !cq->done_color;
@@ -162,8 +157,7 @@ irqreturn_t pdsc_adminq_isr(int irq, void *data)
 static int __pdsc_adminq_post(struct pdsc *pdsc,
 			      struct pdsc_qcq *qcq,
 			      union pds_core_adminq_cmd *cmd,
-			      union pds_core_adminq_comp *comp,
-			      struct pdsc_wait_context *wc)
+			      union pds_core_adminq_comp *comp)
 {
 	struct pdsc_queue *q = &qcq->q;
 	struct pdsc_q_info *q_info;
@@ -205,9 +199,9 @@ static int __pdsc_adminq_post(struct pdsc *pdsc,
 	/* Post the request */
 	index = q->head_idx;
 	q_info = &q->info[index];
-	q_info->wc = wc;
 	q_info->dest = comp;
 	memcpy(q_info->desc, cmd, sizeof(*cmd));
+	reinit_completion(&q_info->completion);
 
 	dev_dbg(pdsc->dev, "head_idx %d tail_idx %d\n",
 		q->head_idx, q->tail_idx);
@@ -231,16 +225,13 @@ int pdsc_adminq_post(struct pdsc *pdsc,
 		     union pds_core_adminq_comp *comp,
 		     bool fast_poll)
 {
-	struct pdsc_wait_context wc = {
-		.wait_completion =
-			COMPLETION_INITIALIZER_ONSTACK(wc.wait_completion),
-	};
 	unsigned long poll_interval = 1;
 	unsigned long poll_jiffies;
 	unsigned long time_limit;
 	unsigned long time_start;
 	unsigned long time_done;
 	unsigned long remaining;
+	struct completion *wc;
 	int err = 0;
 	int index;
 
@@ -250,20 +241,19 @@ int pdsc_adminq_post(struct pdsc *pdsc,
 		return -ENXIO;
 	}
 
-	wc.qcq = &pdsc->adminqcq;
-	index = __pdsc_adminq_post(pdsc, &pdsc->adminqcq, cmd, comp, &wc);
+	index = __pdsc_adminq_post(pdsc, &pdsc->adminqcq, cmd, comp);
 	if (index < 0) {
 		err = index;
 		goto err_out;
 	}
 
+	wc = &pdsc->adminqcq.q.info[index].completion;
 	time_start = jiffies;
 	time_limit = time_start + HZ * pdsc->devcmd_timeout;
 	do {
 		/* Timeslice the actual wait to catch IO errors etc early */
 		poll_jiffies = msecs_to_jiffies(poll_interval);
-		remaining = wait_for_completion_timeout(&wc.wait_completion,
-							poll_jiffies);
+		remaining = wait_for_completion_timeout(wc, poll_jiffies);
 		if (remaining)
 			break;
 
@@ -292,9 +282,11 @@ int pdsc_adminq_post(struct pdsc *pdsc,
 	dev_dbg(pdsc->dev, "%s: elapsed %d msecs\n",
 		__func__, jiffies_to_msecs(time_done - time_start));
 
-	/* Check the results */
-	if (time_after_eq(time_done, time_limit))
+	/* Check the results and clear an un-completed timeout */
+	if (time_after_eq(time_done, time_limit) && !completion_done(wc)) {
 		err = -ETIMEDOUT;
+		complete(wc);
+	}
 
 	dev_dbg(pdsc->dev, "read admin queue completion idx %d:\n", index);
 	dynamic_hex_dump("comp ", DUMP_PREFIX_OFFSET, 16, 1,
diff --git a/drivers/net/ethernet/amd/pds_core/core.c b/drivers/net/ethernet/amd/pds_core/core.c
index 55163457f12b..9512aa4083f0 100644
--- a/drivers/net/ethernet/amd/pds_core/core.c
+++ b/drivers/net/ethernet/amd/pds_core/core.c
@@ -167,8 +167,10 @@ static void pdsc_q_map(struct pdsc_queue *q, void *base, dma_addr_t base_pa)
 	q->base = base;
 	q->base_pa = base_pa;
 
-	for (i = 0, cur = q->info; i < q->num_descs; i++, cur++)
+	for (i = 0, cur = q->info; i < q->num_descs; i++, cur++) {
 		cur->desc = base + (i * q->desc_size);
+		init_completion(&cur->completion);
+	}
 }
 
 static void pdsc_cq_map(struct pdsc_cq *cq, void *base, dma_addr_t base_pa)
diff --git a/drivers/net/ethernet/amd/pds_core/core.h b/drivers/net/ethernet/amd/pds_core/core.h
index 199473112c29..0b53a1fab46d 100644
--- a/drivers/net/ethernet/amd/pds_core/core.h
+++ b/drivers/net/ethernet/amd/pds_core/core.h
@@ -96,7 +96,7 @@ struct pdsc_q_info {
 	unsigned int bytes;
 	unsigned int nbufs;
 	struct pdsc_buf_info bufs[PDS_CORE_MAX_FRAGS];
-	struct pdsc_wait_context *wc;
+	struct completion completion;
 	void *dest;
 };
 
-- 
2.17.1

RE: [PATCH v4 net 0/4] pds_core: updates and fixes

[Keller, Jacob E]

> -----Original Message-----
> From: Shannon Nelson <shannon.nelson@amd.com>
> Sent: Monday, April 21, 2025 10:46 AM
> To: andrew+netdev@lunn.ch; brett.creeley@amd.com; davem@davemloft.net;
> Dumazet, Eric <edumazet@google.com>; kuba@kernel.org; pabeni@redhat.com;
> michal.swiatkowski@linux.intel.com; horms@kernel.org; Keller, Jacob E
> <jacob.e.keller@intel.com>; linux-kernel@vger.kernel.org;
> netdev@vger.kernel.org
> Cc: Shannon Nelson <shannon.nelson@amd.com>
> Subject: [PATCH v4 net 0/4] pds_core: updates and fixes
> 
> This patchset has fixes for issues seen in recent internal testing
> of error conditions and stress handling.
> 
> Note that the first patch in this series is a leftover from an
> earlier patchset that was abandoned:
> Link: https://lore.kernel.org/netdev/20250129004337.36898-2-
> shannon.nelson@amd.com/
> 
> v4:
>  - use init/reinit_completion() rather than COMPLETION_INITIALIZER_ONSTACK()
>  - use completion_done() to protect from completing timed-out requests
> 

Just to confirm, everything looks good to me in this revision!

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>

Re: [PATCH v4 net 0/4] pds_core: updates and fixes

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 21 Apr 2025 10:46:02 -0700 you wrote:
> This patchset has fixes for issues seen in recent internal testing
> of error conditions and stress handling.
> 
> Note that the first patch in this series is a leftover from an
> earlier patchset that was abandoned:
> Link: https://lore.kernel.org/netdev/20250129004337.36898-2-shannon.nelson@amd.com/
> 
> [...]

Here is the summary with links:
  - [v4,net,1/4] pds_core: Prevent possible adminq overflow/stuck condition
    https://git.kernel.org/netdev/net/c/d9e2f070d8af
  - [v4,net,2/4] pds_core: handle unsupported PDS_CORE_CMD_FW_CONTROL result
    https://git.kernel.org/netdev/net/c/2567daad69cd
  - [v4,net,3/4] pds_core: Remove unnecessary check in pds_client_adminq_cmd()
    https://git.kernel.org/netdev/net/c/f9559d818205
  - [v4,net,4/4] pds_core: make wait_context part of q_info
    https://git.kernel.org/netdev/net/c/3f77c3dfffc7

You are awesome, thank you!
-- 
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