linux-kernel - [PATCH] platform/x86: thinkpad_acpi: consistently check fan_get

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Date:   Sat, 12 Mar 2022 06:53:27 -0800
From:   trix@...hat.com
To:     hmh@....eng.br, hdegoede@...hat.com, markgross@...nel.org,
        nathan@...nel.org, ndesaulniers@...gle.com
Cc:     ibm-acpi-devel@...ts.sourceforge.net,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Tom Rix <trix@...hat.com>
Subject: [PATCH] platform/x86: thinkpad_acpi: consistently check fan_get_status return.

From: Tom Rix <trix@...hat.com>

Clang static analysis returns this false positive
thinkpad_acpi.c:8926:19: warning: The left operand
  of '!=' is a garbage value
  (status != 0) ? "enabled" : "disabled", status);
   ~~~~~~ ^

The return of fan_get_status* is checked inconsistenly.
Sometime ret < 0 is an error, sometimes !ret.
Both fan_get_status() and fan_get_status_safe() return
0 on success and return negative otherwise.  Change
the checks for error, ret < 0, into checks for
not success, !ret.

Signed-off-by: Tom Rix <trix@...hat.com>
---
 drivers/platform/x86/thinkpad_acpi.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 708743ec9ae79..c568fae56db29 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -8285,7 +8285,7 @@ static int fan_set_enable(void)
 	case TPACPI_FAN_WR_ACPI_FANS:
 	case TPACPI_FAN_WR_TPEC:
 		rc = fan_get_status(&s);
-		if (rc < 0)
+		if (rc)
 			break;
 
 		/* Don't go out of emergency fan mode */
@@ -8304,7 +8304,7 @@ static int fan_set_enable(void)
 
 	case TPACPI_FAN_WR_ACPI_SFAN:
 		rc = fan_get_status(&s);
-		if (rc < 0)
+		if (rc)
 			break;
 
 		s &= 0x07;
@@ -8843,7 +8843,7 @@ static void fan_suspend(void)
 	/* Store fan status in cache */
 	fan_control_resume_level = 0;
 	rc = fan_get_status_safe(&fan_control_resume_level);
-	if (rc < 0)
+	if (rc)
 		pr_notice("failed to read fan level for later restore during resume: %d\n",
 			  rc);
 
@@ -8864,7 +8864,7 @@ static void fan_resume(void)
 
 	if (!fan_control_allowed ||
 	    !fan_control_resume_level ||
-	    (fan_get_status_safe(&current_level) < 0))
+	    fan_get_status_safe(&current_level))
 		return;
 
 	switch (fan_control_access_mode) {
@@ -8918,7 +8918,7 @@ static int fan_read(struct seq_file *m)
 	case TPACPI_FAN_RD_ACPI_GFAN:
 		/* 570, 600e/x, 770e, 770x */
 		rc = fan_get_status_safe(&status);
-		if (rc < 0)
+		if (rc)
 			return rc;
 
 		seq_printf(m, "status:\t\t%s\n"
@@ -8929,7 +8929,7 @@ static int fan_read(struct seq_file *m)
 	case TPACPI_FAN_RD_TPEC:
 		/* all except 570, 600e/x, 770e, 770x */
 		rc = fan_get_status_safe(&status);
-		if (rc < 0)
+		if (rc)
 			return rc;
 
 		seq_printf(m, "status:\t\t%s\n",
-- 
2.26.3