The refactoring in commit 30984ccf31b7 ("rv: Refactor da_monitor to
minimise macros") replaced per-monitor unique variable names
(da_mon_##name) with a fixed name (da_mon_this).
While this works for 'static' variables (each translation unit gets its
own copy), DEFINE_PER_CPU internally generates a non-static dummy
variable __pcpu_unique_<n> for each per-cpu definition. The requirement
for this variable to be unique although static exists for modules on
specific architectures (alpha) and if the kernel is built with
CONFIG_DEBUG_FORCE_WEAK_PER_CPU (e.g. Fedora's debug kernel).
When multiple per-cpu monitors (e.g. sco and sts) are built-in
simultaneously, they all produce the same __pcpu_unique_da_mon_this
symbol, causing a link error:
ld: kernel/trace/rv/monitors/sts/sts.o: multiple definition of
`__pcpu_unique_da_mon_this';
kernel/trace/rv/monitors/sco/sco.o: first defined here
Fix this by introducing a DA_MON_NAME macro that expands to a
per-monitor unique name (da_mon_<MONITOR_NAME>) via the existing
CONCATENATE helper. This restores the uniqueness that was present
before the refactoring.
Fixes: 30984ccf31b7 ("rv: Refactor da_monitor to minimise macros")
Reviewed-by: Gabriele Monaco <[email protected]>
Signed-off-by: Mikhail Gavrilov <[email protected]>
---
Changes since v1:
https://lore.kernel.org/all/[email protected]/
- Updated commit message with details on when __pcpu_unique_ uniqueness
is required (alpha modules, CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
- Added code comment above DA_MON_NAME explaining the rationale
include/rv/da_monitor.h | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/include/rv/da_monitor.h b/include/rv/da_monitor.h
index db11d41bb438..7511f5464c48 100644
--- a/include/rv/da_monitor.h
+++ b/include/rv/da_monitor.h
@@ -20,6 +20,12 @@
#include <linux/bug.h>
#include <linux/sched.h>
+/*
+ * Per-cpu variables require a unique name although static in some
+ * configurations (e.g. CONFIG_DEBUG_FORCE_WEAK_PER_CPU or alpha modules).
+ */
+#define DA_MON_NAME CONCATENATE(da_mon_, MONITOR_NAME)
+
static struct rv_monitor rv_this;
static void react(enum states curr_state, enum events event)
@@ -183,14 +189,14 @@ static inline bool da_event(struct da_monitor *da_mon,
struct task_struct *tsk,
/*
* global monitor (a single variable)
*/
-static struct da_monitor da_mon_this;
+static struct da_monitor DA_MON_NAME;
/*
* da_get_monitor - return the global monitor address
*/
static struct da_monitor *da_get_monitor(void)
{
- return &da_mon_this;
+ return &DA_MON_NAME;
}
/*
@@ -223,14 +229,14 @@ static inline void da_monitor_destroy(void) { }
/*
* per-cpu monitor variables
*/
-static DEFINE_PER_CPU(struct da_monitor, da_mon_this);
+static DEFINE_PER_CPU(struct da_monitor, DA_MON_NAME);
/*
* da_get_monitor - return current CPU monitor address
*/
static struct da_monitor *da_get_monitor(void)
{
- return this_cpu_ptr(&da_mon_this);
+ return this_cpu_ptr(&DA_MON_NAME);
}
/*
@@ -242,7 +248,7 @@ static void da_monitor_reset_all(void)
int cpu;
for_each_cpu(cpu, cpu_online_mask) {
- da_mon = per_cpu_ptr(&da_mon_this, cpu);
+ da_mon = per_cpu_ptr(&DA_MON_NAME, cpu);
da_monitor_reset(da_mon);
}
}
--
2.53.0
