linux-kernel - [PATCH v2 1/2] drivers: base: cacheinfo: Do not populate sysfs for unknown cache types

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Message-Id: <1536942489-4018-2-git-send-email-jhugo@codeaurora.org>
Date:   Fri, 14 Sep 2018 10:28:08 -0600
From:   Jeffrey Hugo <jhugo@...eaurora.org>
To:     sudeep.holla@....com, gregkh@...uxfoundation.org,
        rjw@...ysocki.net, linux-acpi@...r.kernel.org,
        jeremy.linton@....com
Cc:     linux-kernel@...r.kernel.org, vkilari@...eaurora.org,
        Jeffrey Hugo <jhugo@...eaurora.org>
Subject: [PATCH v2 1/2] drivers: base: cacheinfo: Do not populate sysfs for unknown cache types

If a cache has an unknown type because neither the hardware nor the
firmware told us, an entry in the sysfs tree will be made, but the type
file will not be present.  lscpu depends on the type file being present
for every entry, and will error out without printing system information
if lscpu cannot open the type file.

Presenting information about a cache without indicating its type is not
useful, therefore if we hit a cache with an unknown type, stop populating
sysfs so that userspace has the maximum amount of useful information.

This addresses the following lscpu error, which prevents any output.
lscpu: cannot open /sys/devices/system/cpu/cpu0/cache/index3/type: No such
file or directory

Suggested-by: Sudeep Holla <sudeep.holla@....com>
Signed-off-by: Jeffrey Hugo <jhugo@...eaurora.org>
---
 drivers/base/cacheinfo.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 5d5b598..cf78fa6 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -615,6 +615,8 @@ static int cache_add_dev(unsigned int cpu)
 		this_leaf = this_cpu_ci->info_list + i;
 		if (this_leaf->disable_sysfs)
 			continue;
+		if (this_leaf->type == CACHE_TYPE_NOCACHE)
+			break;
 		cache_groups = cache_get_attribute_groups(this_leaf);
 		ci_dev = cpu_device_create(parent, this_leaf, cache_groups,
 					   "index%1u", i);
-- 
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