linux-acpi.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>, Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <garsilva@embeddedor.com>
Subject: [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit
Date: Tue, 6 Feb 2018 17:36:17 -0600	[thread overview]
Message-ID: <20180206233617.GA30829@embeddedgus> (raw)

Add suffix ULL to constant 500 in order to give the compiler complete
information about the proper arithmetic to use. Notice that this
constant is used in a context that expects an expression of type
u64 (64 bits, unsigned).

The expression NUM_RETRIES * cppc_ss->latency at line 578, which at
preprocessing time translates to 500 * cppc_ss->latency is currently
being evaluated using 32-bit arithmetic.

Addresses-Coverity-ID: 1382602
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
Notice that another option is to cast NUM_RETRIES to u64 at line 578,
but as there is only one instace in which this macro is being used I
think adding the ULL is just enough.

 drivers/acpi/cppc_acpi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 06ea474..0afbb26 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -119,7 +119,7 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
  * to PCC commands. Keeping it high enough to cover emulators where
  * the processors run painfully slow.
  */
-#define NUM_RETRIES 500
+#define NUM_RETRIES 500ULL
 
 struct cppc_attr {
 	struct attribute attr;
-- 
2.7.4


             reply	other threads:[~2018-02-06 23:36 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-06 23:36 Gustavo A. R. Silva [this message]
2018-02-08  9:49 ` [PATCH] ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit Rafael J. Wysocki
2018-02-08 16:40   ` Gustavo A. R. Silva

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180206233617.GA30829@embeddedgus \
    --to=gustavo@embeddedor.com \
    --cc=garsilva@embeddedor.com \
    --cc=lenb@kernel.org \
    --cc=linux-acpi@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rjw@rjwysocki.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).