Re: [PATCH v2] perf/arm_pmu_platform: Fix an error message related to dev_err_probe() usage

From: Robin Murphy
Date: Mon Aug 08 2022 - 10:58:20 EST


On 2022-08-05 21:55, Christophe JAILLET wrote:
dev_err() is a macro that expand dev_fmt, but dev_err_probe() is a
function and cannot perform this macro expansion.

So hard code the "hw perfevents: " prefix and dd a comment explaining why.

Fixes: 11fa1dc8020a ("perf/arm_pmu_platform: Use dev_err_probe() for IRQ errors")
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
Untested, but I can't see how it could work.

v1 --> v2
- fix a typo in the comment
---
drivers/perf/arm_pmu_platform.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/perf/arm_pmu_platform.c b/drivers/perf/arm_pmu_platform.c
index 513de1f54e2d..02cca4b8f0fd 100644
--- a/drivers/perf/arm_pmu_platform.c
+++ b/drivers/perf/arm_pmu_platform.c
@@ -101,8 +101,11 @@ static int pmu_parse_irqs(struct arm_pmu *pmu)
struct device *dev = &pdev->dev;
num_irqs = platform_irq_count(pdev);
- if (num_irqs < 0)
- return dev_err_probe(dev, num_irqs, "unable to count PMU IRQs\n");
+ if (num_irqs < 0) {
+ /* dev_err_probe() does not handle dev_fmt, so hard-code the prefix */
+ return dev_err_probe(dev, num_irqs,
+ "hw perfevents: unable to count PMU IRQs\n");

Why not use dev_fmt directly? But even better, is there any practical reason why this couldn't be fixed at the source by indirecting dev_err_probe() through a macro wrapper just like all its friends:

#define dev_err_probe(dev, err, fmt, ...) \
_dev_err_probe(dev, err, dev_fmt(fmt), ##__VA_ARGS__)

?

Thanks,
Robin.

+ }
/*
* In this case we have no idea which CPUs are covered by the PMU.