Messages in this thread | | | Date | Mon, 21 Aug 2023 10:29:22 +0100 | Subject | Re: [PATCH v5] perf: arm_cspmu: Separate Arm and vendor module | From | Robin Murphy <> |
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On 2023-08-19 21:11, Besar Wicaksono wrote: [...] >>> +void arm_cspmu_impl_unregister(const struct arm_cspmu_impl_match >> *impl_match) >>> +{ >>> + struct device *dev; >>> + struct arm_cspmu_impl_match *match; >>> + >>> + match = arm_cspmu_impl_match_get(impl_match->pmiidr_val); >>> + >>> + WARN_ON(!match);
Nit: do "if (WARN_ON(!match)) return;" rather than indenting almost the whole function.
>>> + >>> + if (match) { >>> + /* Unbind the driver from all matching backend devices. */ >>> +dev_release: >>> + dev = driver_find_device(&arm_cspmu_driver.driver, NULL, >>> + match, arm_cspmu_match_device); >>> + if (dev) { >>> + device_release_driver(dev); >>> + goto dev_release; >>> + } >> >> minor nit: We could simply do : >> >> static int arm_cspmu_release_driver(struct device *dev, void *data) >> { >> struct arm_cspmu *cspmu = >> platform_get_drvdata(to_platform_device(dev)); >> >> if (cspmu && cspmu->impl.match == match) >> device_release_driver(dev); >> return 0; >> } >> >> ret = driver_for_each_device(&driver, NULL, match, >> arm_csmpu_release_driver); >> > > It doesn’t seem to work for me. > Is it safe to release while iterating via driver_for_each_device ?
Looking at the klist code it doesn't *obviously* appear safe to modify the list during iteration, so probably best not to risk it anyway. However, please try to write this loop as an actual loop, e.g.:
while ((dev = driver_find_device())) device_release_driver();
At first glance I thought there was a bug here that it's only processing a single device, then eventually I saw the goto and my thought changed to "Eww..."
Thanks, Robin.
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