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From: Nathan Chancellor <natechancellor@gmail.com>
To: Tyrel Datwyler <tyreld@linux.ibm.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	Nathan Chancellor <natechancellor@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>
Subject: [PATCH v2] PCI: rpaphp: Avoid a sometimes-uninitialized warning
Date: Mon,  3 Jun 2019 15:11:58 -0700	[thread overview]
Message-ID: <20190603221157.58502-1-natechancellor@gmail.com> (raw)
In-Reply-To: <20190603174323.48251-1-natechancellor@gmail.com>

When building with -Wsometimes-uninitialized, clang warns:

drivers/pci/hotplug/rpaphp_core.c:243:14: warning: variable 'fndit' is
used uninitialized whenever 'for' loop exits because its condition is
false [-Wsometimes-uninitialized]
        for (j = 0; j < entries; j++) {
                    ^~~~~~~~~~~
drivers/pci/hotplug/rpaphp_core.c:256:6: note: uninitialized use occurs
here
        if (fndit)
            ^~~~~
drivers/pci/hotplug/rpaphp_core.c:243:14: note: remove the condition if
it is always true
        for (j = 0; j < entries; j++) {
                    ^~~~~~~~~~~
drivers/pci/hotplug/rpaphp_core.c:233:14: note: initialize the variable
'fndit' to silence this warning
        int j, fndit;
                    ^
                     = 0

fndit is only used to gate a sprintf call, which can be moved into the
loop to simplify the code and eliminate the local variable, which will
fix this warning.

Link: https://github.com/ClangBuiltLinux/linux/issues/504
Fixes: 2fcf3ae508c2 ("hotplug/drc-info: Add code to search ibm,drc-info property")
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---

v1 -> v2:

* Eliminate fndit altogether by shuffling the sprintf call into the for
  loop and changing the if conditional, as suggested by Nick.

 drivers/pci/hotplug/rpaphp_core.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/hotplug/rpaphp_core.c b/drivers/pci/hotplug/rpaphp_core.c
index bcd5d357ca23..c3899ee1db99 100644
--- a/drivers/pci/hotplug/rpaphp_core.c
+++ b/drivers/pci/hotplug/rpaphp_core.c
@@ -230,7 +230,7 @@ static int rpaphp_check_drc_props_v2(struct device_node *dn, char *drc_name,
 	struct of_drc_info drc;
 	const __be32 *value;
 	char cell_drc_name[MAX_DRC_NAME_LEN];
-	int j, fndit;
+	int j;
 
 	info = of_find_property(dn->parent, "ibm,drc-info", NULL);
 	if (info == NULL)
@@ -245,17 +245,13 @@ static int rpaphp_check_drc_props_v2(struct device_node *dn, char *drc_name,
 
 		/* Should now know end of current entry */
 
-		if (my_index > drc.last_drc_index)
-			continue;
-
-		fndit = 1;
-		break;
+		/* Found it */
+		if (my_index <= drc.last_drc_index) {
+			sprintf(cell_drc_name, "%s%d", drc.drc_name_prefix,
+				my_index);
+			break;
+		}
 	}
-	/* Found it */
-
-	if (fndit)
-		sprintf(cell_drc_name, "%s%d", drc.drc_name_prefix, 
-			my_index);
 
 	if (((drc_name == NULL) ||
 	     (drc_name && !strcmp(drc_name, cell_drc_name))) &&
-- 
2.22.0.rc3


WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <natechancellor@gmail.com>
To: Tyrel Datwyler <tyreld@linux.ibm.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-pci@vger.kernel.org,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	Bjorn Helgaas <bhelgaas@google.com>,
	Nathan Chancellor <natechancellor@gmail.com>,
	linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v2] PCI: rpaphp: Avoid a sometimes-uninitialized warning
Date: Mon,  3 Jun 2019 15:11:58 -0700	[thread overview]
Message-ID: <20190603221157.58502-1-natechancellor@gmail.com> (raw)
In-Reply-To: <20190603174323.48251-1-natechancellor@gmail.com>

When building with -Wsometimes-uninitialized, clang warns:

drivers/pci/hotplug/rpaphp_core.c:243:14: warning: variable 'fndit' is
used uninitialized whenever 'for' loop exits because its condition is
false [-Wsometimes-uninitialized]
        for (j = 0; j < entries; j++) {
                    ^~~~~~~~~~~
drivers/pci/hotplug/rpaphp_core.c:256:6: note: uninitialized use occurs
here
        if (fndit)
            ^~~~~
drivers/pci/hotplug/rpaphp_core.c:243:14: note: remove the condition if
it is always true
        for (j = 0; j < entries; j++) {
                    ^~~~~~~~~~~
drivers/pci/hotplug/rpaphp_core.c:233:14: note: initialize the variable
'fndit' to silence this warning
        int j, fndit;
                    ^
                     = 0

fndit is only used to gate a sprintf call, which can be moved into the
loop to simplify the code and eliminate the local variable, which will
fix this warning.

Link: https://github.com/ClangBuiltLinux/linux/issues/504
Fixes: 2fcf3ae508c2 ("hotplug/drc-info: Add code to search ibm,drc-info property")
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---

v1 -> v2:

* Eliminate fndit altogether by shuffling the sprintf call into the for
  loop and changing the if conditional, as suggested by Nick.

 drivers/pci/hotplug/rpaphp_core.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/hotplug/rpaphp_core.c b/drivers/pci/hotplug/rpaphp_core.c
index bcd5d357ca23..c3899ee1db99 100644
--- a/drivers/pci/hotplug/rpaphp_core.c
+++ b/drivers/pci/hotplug/rpaphp_core.c
@@ -230,7 +230,7 @@ static int rpaphp_check_drc_props_v2(struct device_node *dn, char *drc_name,
 	struct of_drc_info drc;
 	const __be32 *value;
 	char cell_drc_name[MAX_DRC_NAME_LEN];
-	int j, fndit;
+	int j;
 
 	info = of_find_property(dn->parent, "ibm,drc-info", NULL);
 	if (info == NULL)
@@ -245,17 +245,13 @@ static int rpaphp_check_drc_props_v2(struct device_node *dn, char *drc_name,
 
 		/* Should now know end of current entry */
 
-		if (my_index > drc.last_drc_index)
-			continue;
-
-		fndit = 1;
-		break;
+		/* Found it */
+		if (my_index <= drc.last_drc_index) {
+			sprintf(cell_drc_name, "%s%d", drc.drc_name_prefix,
+				my_index);
+			break;
+		}
 	}
-	/* Found it */
-
-	if (fndit)
-		sprintf(cell_drc_name, "%s%d", drc.drc_name_prefix, 
-			my_index);
 
 	if (((drc_name == NULL) ||
 	     (drc_name && !strcmp(drc_name, cell_drc_name))) &&
-- 
2.22.0.rc3


  parent reply	other threads:[~2019-06-03 22:13 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-03 17:43 [PATCH] PCI: rpaphp: Avoid a sometimes-uninitialized warning Nathan Chancellor
2019-06-03 17:43 ` Nathan Chancellor
2019-06-03 21:07 ` Nick Desaulniers
2019-06-03 21:07   ` Nick Desaulniers
2019-06-03 21:51   ` Nathan Chancellor
2019-06-03 21:51     ` Nathan Chancellor
2019-06-03 22:11 ` Nathan Chancellor [this message]
2019-06-03 22:11   ` [PATCH v2] " Nathan Chancellor
2019-06-04  0:03   ` Tyrel Datwyler
2019-06-04  0:03     ` Tyrel Datwyler
2019-06-27 19:18   ` Nathan Chancellor
2019-06-27 19:18     ` Nathan Chancellor
2019-06-28  2:57   ` Joel Savitz
2019-06-28  2:57     ` Joel Savitz
2019-07-22  2:43   ` Nathan Chancellor
2019-07-22  2:43     ` Nathan Chancellor
2019-07-22  4:05     ` Michael Ellerman
2019-07-22  4:05       ` Michael Ellerman
2019-08-02  0:11       ` Bjorn Helgaas
2019-08-02  0:11         ` Bjorn Helgaas
2019-08-02 12:24         ` Michael Ellerman
2019-08-02 12:24           ` Michael Ellerman
2019-08-10 10:20   ` Michael Ellerman
2019-06-04  6:24 ` [PATCH] " Christophe Leroy
2019-06-04  6:24   ` Christophe Leroy

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