fix unused-but-set-global warnings

Clang 23 adds -Wunused-but-set-global, which reports file scope variables that are assigned but never read. It is enabled by -Wall and does not appear with gcc or with clang 20 through 22.

Three of these are dead variables and are simply removed. The fourth, 'alive' in dpaa_of.c, is a real debug aid: it is only read by DPAAX_HWWARN, which discards its condition when RTE_LIBRTE_DPAAX_DEBUG is not defined. That one is fixed by making the empty expansion consume its argument, which keeps the condition compiled in both builds and covers every other DPAAX_HWWARN user as well.

The patches are independent and touch four unrelated drivers.

Stephen Hemminger (4):
common/dpaax: fix unused variable warning in non-debug build bus/dpaa: remove unused qman_clk variable common/zsda: remove unused device counter net/qede: remove unused app version variable

 drivers/bus/dpaa/base/qbman/qman_driver.c | 4 ----
 drivers/common/dpaax/dpaax_logs.h         | 3 ++-
 drivers/common/zsda/zsda_device.c         | 5 -----
 drivers/net/qede/qede_debug.c             | 9 ---------
 4 files changed, 2 insertions(+), 19 deletions(-)

2.53.0

Fix compiler warning on clang-23.

dpaa_of.c:14:12: warning: variable 'alive' set but not used
[-Wunused-but-set-global]

The 'alive' flag is only read by DPAAX_HWWARN, which expands to an empty statement and discards its condition unless RTE_LIBRTE_DPAAX_DEBUG is defined. Make the empty expansion consume its argument so the condition is still checked in a non-debug build.

---
 drivers/common/dpaax/dpaax_logs.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 90f0c98863..431a16f45a 100644
@@ -5,6 +5,7 @@
 #ifndef _DPAAX_LOGS_H_
 #define _DPAAX_LOGS_H_
 
+#include <rte_common.h>
 #include <rte_log.h>
 
 extern int dpaax_logger;

@@ -17,7 +18,7 @@ extern int dpaax_logger;
 			DPAAX_LOG(DEBUG, "WARN: " fmt, ##__VA_ARGS__); \
 	} while (0)
 #else
-#define DPAAX_HWWARN(cond, fmt, ...) do { } while (0)
+#define DPAAX_HWWARN(cond, fmt, ...) do { RTE_SET_USED(cond); } while (0)
 #endif
 
 #define DPAAX_LOG(level, ...) \

2.53.0

Not that important, the issue probably predates this commit.
And looking at this change, it seems DPAA_BUS_HWWARN is dead code since then.

Otherwise lgtm.

David Marchand

That is when the device-tree warning was added.
The history scan looks right.

It seems like it should either be removed as irrelevant or made into a regular warning. But that is up to Hemant and Sachin to decide; I just want clean builds for now.

We will plan to remove this definition in future.

The driver was recording the clock frequency and never using it.

clang 23 reports:

qman_driver.c:27:12: warning: variable 'qman_clk' set but not used
[-Wunused-but-set-global]

Remove the variable and the dead store.

---
 drivers/bus/dpaa/base/qbman/qman_driver.c | 4 ----
 1 file changed, 4 deletions(-)

index 45b094e0c6..bbe2640c52 100644
@@ -23,8 +23,6 @@ u16 qm_channel_pme = QMAN_CHANNEL_PME;
 
 /* Ccsr map address to access ccsrbased register */
 static void *qman_ccsr_map;
-/* The qman clock frequency */
-static u32 qman_clk;
 
 static __thread int qmfd = -1;
 static __thread struct qm_portal_config qpcfg;

@@ -371,8 +369,6 @@ int qman_global_init(void)
 	clk = of_get_property(dt_node, "clock-frequency", NULL);
 	if (!clk)
 		pr_warn("Can't find Qman clock frequency\n");
-	else
-		qman_clk = be32_to_cpu(*clk);
 
 #ifdef CONFIG_FSL_QMAN_FQ_LOOKUP
 	return qman_setup_fq_lookup_table(CONFIG_FSL_QMAN_FQ_LOOKUP_MAX);

2.53.0

zsda_nb_pci_devices is incremented when a PCI device is allocated and decremented when it is released, but the count is never read.

clang 23 reports:

zsda_device.c:10:12: warning: variable 'zsda_nb_pci_devices' set but
not used [-Wunused-but-set-global]

Remove the counter and the three sites that update it.

---
 drivers/common/zsda/zsda_device.c | 5 -----
 1 file changed, 5 deletions(-)

index 72f017c699..280a51f9b3 100644
@@ -7,7 +7,6 @@
 
 /* per-process array of device data */
 struct zsda_device_info zsda_devs[RTE_PMD_ZSDA_MAX_PCI_DEVICES];
-static int zsda_nb_pci_devices;
 
 /*
  * The set of PCI devices this driver supports

@@ -85,7 +84,6 @@ zsda_pci_device_allocate(struct rte_pci_device *pci_dev)
 		zsda_pci_dev = mz->addr;
 		zsda_devs[zsda_pci_dev->zsda_dev_id].mz = mz;
 		zsda_devs[zsda_pci_dev->zsda_dev_id].pci_dev = pci_dev;
-		zsda_nb_pci_devices++;
 		return zsda_pci_dev;
 	}
 

@@ -114,8 +112,6 @@ zsda_pci_device_allocate(struct rte_pci_device *pci_dev)
 	zsda_pci_dev->pci_dev = pci_dev;
 	zsda_devs[zsda_dev_id].pci_dev = pci_dev;
 
-	zsda_nb_pci_devices++;
-
 	return zsda_pci_dev;
 }
 

@@ -141,7 +137,6 @@ zsda_pci_device_release(const struct rte_pci_device *pci_dev)
 			rte_memzone_free(inst->mz);
 
 		memset(inst, 0, sizeof(struct zsda_device_info));
-		zsda_nb_pci_devices--;
 	}
 	return 0;
 }

2.53.0

qed_dbg_set_app_ver() validates the caller's version and stores it. But the variable s_app_ver is never used in DPDK driver.

clang 23 reports:

qede_debug.c:820:12: warning: variable 's_app_ver' set but not used
[-Wunused-but-set-global]

Remove the variable and the dead store.

---
 drivers/net/qede/qede_debug.c | 9 ---------
 1 file changed, 9 deletions(-)

index 1d3147b724..8afaa5c108 100644
@@ -812,13 +812,6 @@ static struct split_type_defs s_split_type_defs[] = {
 	{"vf"}
 };
 
-/******************************** Variables *********************************/
-
-/**
- * The version of the calling app
- */
-static u32 s_app_ver;
-
 /**************************** Private Functions ******************************/
 
 /* Reads and returns a single dword from the specified unaligned buffer */

@@ -4869,8 +4862,6 @@ enum dbg_status qed_dbg_set_app_ver(u32 ver)
 	if (ver < TOOLS_VERSION)
 		return DBG_STATUS_UNSUPPORTED_APP_VERSION;
 
-	s_app_ver = ver;
-
 	return DBG_STATUS_OK;
 }
 

2.53.0

Maybe go one step further?
qed_dbg_set_app_ver() looks useless.

David Marchand

Yes it is useless code. Looks like inherited from Linux driver.

Clang 23 adds -Wunused-but-set-global, which reports file scope variables that are assigned but never read. It is enabled by -Wall and does not appear with gcc or with clang 20 through 22.

Three of these are dead variables and are simply removed. The fourth, 'alive' in dpaa_of.c, is a real debug aid: it is only read by DPAAX_HWWARN, which discards its condition when RTE_LIBRTE_DPAAX_DEBUG is not defined. That one is fixed by making the empty expansion consume its argument, which keeps the condition compiled in both builds and covers every other DPAAX_HWWARN user as well.

v2 - remove more unused code as suggested.

Stephen Hemminger (4):
common/dpaax: fix unused variable warning in non-debug build bus/dpaa: remove unused qman_clk variable common/zsda: remove unused device counter net/qede: remove unused app version variable

 drivers/bus/dpaa/base/qbman/qman_driver.c |  4 ----
 drivers/common/dpaax/dpaax_logs.h         |  3 ++-
 drivers/common/zsda/zsda_device.c         |  5 -----
 drivers/net/qede/qede_debug.c             | 20 --------------------
 4 files changed, 2 insertions(+), 30 deletions(-)

2.53.0

Fix compiler warning on clang-23.

dpaa_of.c:14:12: warning: variable 'alive' set but not used
[-Wunused-but-set-global]

The 'alive' flag is only read by DPAAX_HWWARN, which expands to an empty statement and discards its condition unless RTE_LIBRTE_DPAAX_DEBUG is defined. Make the empty expansion consume its argument so the condition is still checked in a non-debug build.

---
 drivers/common/dpaax/dpaax_logs.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 90f0c98863..431a16f45a 100644
@@ -5,6 +5,7 @@
 #ifndef _DPAAX_LOGS_H_
 #define _DPAAX_LOGS_H_
 
+#include <rte_common.h>
 #include <rte_log.h>
 
 extern int dpaax_logger;

@@ -17,7 +18,7 @@ extern int dpaax_logger;
 			DPAAX_LOG(DEBUG, "WARN: " fmt, ##__VA_ARGS__); \
 	} while (0)
 #else
-#define DPAAX_HWWARN(cond, fmt, ...) do { } while (0)
+#define DPAAX_HWWARN(cond, fmt, ...) do { RTE_SET_USED(cond); } while (0)
 #endif
 
 #define DPAAX_LOG(level, ...) \

2.53.0

The driver was recording the clock frequency and never using it.

clang 23 reports:

qman_driver.c:27:12: warning: variable 'qman_clk' set but not used
[-Wunused-but-set-global]

Remove the variable and the dead store.

---
 drivers/bus/dpaa/base/qbman/qman_driver.c | 4 ----
 1 file changed, 4 deletions(-)

index 45b094e0c6..bbe2640c52 100644
@@ -23,8 +23,6 @@ u16 qm_channel_pme = QMAN_CHANNEL_PME;
 
 /* Ccsr map address to access ccsrbased register */
 static void *qman_ccsr_map;
-/* The qman clock frequency */
-static u32 qman_clk;
 
 static __thread int qmfd = -1;
 static __thread struct qm_portal_config qpcfg;

@@ -371,8 +369,6 @@ int qman_global_init(void)
 	clk = of_get_property(dt_node, "clock-frequency", NULL);
 	if (!clk)
 		pr_warn("Can't find Qman clock frequency\n");
-	else
-		qman_clk = be32_to_cpu(*clk);
 
 #ifdef CONFIG_FSL_QMAN_FQ_LOOKUP
 	return qman_setup_fq_lookup_table(CONFIG_FSL_QMAN_FQ_LOOKUP_MAX);

2.53.0

zsda_nb_pci_devices is incremented when a PCI device is allocated and decremented when it is released, but the count is never read.

clang 23 reports:

zsda_device.c:10:12: warning: variable 'zsda_nb_pci_devices' set but
not used [-Wunused-but-set-global]

Remove the counter and the three sites that update it.

---
The CI AI review of this patch was hallucinating and fabricated functions that don't exist.

 drivers/common/zsda/zsda_device.c | 5 -----
 1 file changed, 5 deletions(-)

index 72f017c699..280a51f9b3 100644
@@ -7,7 +7,6 @@
 
 /* per-process array of device data */
 struct zsda_device_info zsda_devs[RTE_PMD_ZSDA_MAX_PCI_DEVICES];
-static int zsda_nb_pci_devices;
 
 /*
  * The set of PCI devices this driver supports

@@ -85,7 +84,6 @@ zsda_pci_device_allocate(struct rte_pci_device *pci_dev)
 		zsda_pci_dev = mz->addr;
 		zsda_devs[zsda_pci_dev->zsda_dev_id].mz = mz;
 		zsda_devs[zsda_pci_dev->zsda_dev_id].pci_dev = pci_dev;
-		zsda_nb_pci_devices++;
 		return zsda_pci_dev;
 	}
 

@@ -114,8 +112,6 @@ zsda_pci_device_allocate(struct rte_pci_device *pci_dev)
 	zsda_pci_dev->pci_dev = pci_dev;
 	zsda_devs[zsda_dev_id].pci_dev = pci_dev;
 
-	zsda_nb_pci_devices++;
-
 	return zsda_pci_dev;
 }
 

@@ -141,7 +137,6 @@ zsda_pci_device_release(const struct rte_pci_device *pci_dev)
 			rte_memzone_free(inst->mz);
 
 		memset(inst, 0, sizeof(struct zsda_device_info));
-		zsda_nb_pci_devices--;
 	}
 	return 0;
 }

2.53.0

qed_dbg_set_app_ver() validates the caller's version and stores it. clang 23 reports:

qede_debug.c:820:12: warning: variable 's_app_ver' set but not used
[-Wunused-but-set-global]

Since the whole qed_dbg_set_app_ver() function is doing nothing remove it.

---
 drivers/net/qede/qede_debug.c | 20 --------------------
 1 file changed, 20 deletions(-)

index 1d3147b724..d14ef93a3c 100644
@@ -812,13 +812,6 @@ static struct split_type_defs s_split_type_defs[] = {
 	{"vf"}
 };
 
-/******************************** Variables *********************************/
-
-/**
- * The version of the calling app
- */
-static u32 s_app_ver;
-
 /**************************** Private Functions ******************************/
 
 /* Reads and returns a single dword from the specified unaligned buffer */

@@ -4864,16 +4857,6 @@ enum dbg_status qed_dbg_set_bin_ptr(struct ecore_hwfn *p_hwfn,
 	return DBG_STATUS_OK;
 }
 
-enum dbg_status qed_dbg_set_app_ver(u32 ver)
-{
-	if (ver < TOOLS_VERSION)
-		return DBG_STATUS_UNSUPPORTED_APP_VERSION;
-
-	s_app_ver = ver;
-
-	return DBG_STATUS_OK;
-}
-
 bool qed_read_fw_info(struct ecore_hwfn *p_hwfn,
 		      struct ecore_ptt *p_ptt, struct fw_info *fw_info)
 {

@@ -8087,9 +8070,6 @@ void qed_dbg_pf_init(struct ecore_dev *edev)
 
 	OSAL_MUTEX_INIT(&edev->dbg_lock);
 
-	/* Sync ver with debugbus qed code */
-	qed_dbg_set_app_ver(TOOLS_VERSION);
-
 	/* Debug values are after init values.
 	 * The offset is the first dword of the file.
 	 */

2.53.0

For the series:

David Marchand

Applied to next-net; so that clang 23 build tests can run across all drivers