linux-kernel - RE: [PATCH] cxl/mbox: Fix CEL logic for poison and security commands

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Message-ID: <6500e8a179440_12747294a3@dwillia2-xfh.jf.intel.com.notmuch>
Date:   Tue, 12 Sep 2023 15:39:29 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Ira Weiny <ira.weiny@...el.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Ira Weiny <ira.weiny@...el.com>
Subject: RE: [PATCH] cxl/mbox: Fix CEL logic for poison and security commands

Ira Weiny wrote:
> The following debug output was observed while testing CXL
> 
> cxl_core:cxl_walk_cel:721: cxl_mock_mem cxl_mem.0: Opcode 0x4300 unsupported by driver
> 
> opcode 0x4300 (Get Poison) is supported by the driver and the mock
> device supports it.  The logic should be checking that the opcode is
> both not poison and not security.
> 
> Fix the logic to allow poison and security commands.
> 
> Fixes: ad64f5952ce3 ("cxl/memdev: Only show sanitize sysfs files when supported")
> Cc: Davidlohr Bueso <dave@...olabs.net>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> ---
>  drivers/cxl/core/mbox.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> index ca60bb8114f2..b315bdab9197 100644
> --- a/drivers/cxl/core/mbox.c
> +++ b/drivers/cxl/core/mbox.c
> @@ -716,8 +716,8 @@ static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
>  		u16 opcode = le16_to_cpu(cel_entry[i].opcode);
>  		struct cxl_mem_command *cmd = cxl_mem_find_command(opcode);
>  
> -		if (!cmd && (!cxl_is_poison_command(opcode) ||
> -			     !cxl_is_security_command(opcode))) {
> +		if (!cmd && !cxl_is_poison_command(opcode) &&
> +		    !cxl_is_security_command(opcode)) {

Given that this is going to be a recurring pattern to add optional
command support, I am not a fan of continuing to expand this boolean
algebra eye exam.

How about the following to only do the validation check and enabling in
one place:


diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index ca60bb8114f2..4df4f614f490 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -715,24 +715,25 @@ static void cxl_walk_cel(struct cxl_memdev_state *mds, size_t size, u8 *cel)
 	for (i = 0; i < cel_entries; i++) {
 		u16 opcode = le16_to_cpu(cel_entry[i].opcode);
 		struct cxl_mem_command *cmd = cxl_mem_find_command(opcode);
+		int enabled = 0;
 
-		if (!cmd && (!cxl_is_poison_command(opcode) ||
-			     !cxl_is_security_command(opcode))) {
-			dev_dbg(dev,
-				"Opcode 0x%04x unsupported by driver\n", opcode);
-			continue;
-		}
-
-		if (cmd)
+		if (cmd) {
 			set_bit(cmd->info.id, mds->enabled_cmds);
+			enabled++;
+		}
 
-		if (cxl_is_poison_command(opcode))
+		if (cxl_is_poison_command(opcode)) {
 			cxl_set_poison_cmd_enabled(&mds->poison, opcode);
+			enabled++;
+		}
 
-		if (cxl_is_security_command(opcode))
+		if (cxl_is_security_command(opcode)) {
 			cxl_set_security_cmd_enabled(&mds->security, opcode);
+			enabled++;
+		}
 
-		dev_dbg(dev, "Opcode 0x%04x enabled\n", opcode);
+		dev_dbg(dev, "Opcode 0x%04x %s\n", opcode,
+			enabled ? "enabled" : "unsupported by driver");
 	}
 }