From: Peter Hilber Date: Thu, 1 Feb 2024 01:04:51 +0000 (+0100) Subject: timekeeping: Evaluate system_counterval_t.cs_id instead of .cs X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=4b7f521229ef4eee06848427d865954e6e0e3675;p=linux.git timekeeping: Evaluate system_counterval_t.cs_id instead of .cs Clocksource pointers can be problematic to obtain for drivers which are not clocksource drivers themselves. In particular, the RFC virtio_rtc driver [1] would require a new helper function to obtain a pointer to the ARM Generic Timer clocksource. The ptp_kvm driver also required a similar workaround. Address this by evaluating the clocksource ID, rather than the clocksource pointer, of struct system_counterval_t. By this, setting the clocksource pointer becomes unneeded, and get_device_system_crosststamp() callers will no longer need to supply clocksource pointers. All relevant clocksource drivers provide the ID, so this change is not changing the behaviour. [1] https://lore.kernel.org/lkml/20231218073849.35294-1-peter.hilber@opensynergy.com/ Signed-off-by: Peter Hilber Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240201010453.2212371-7-peter.hilber@opensynergy.com --- diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index ca234fa4cc046..3538c5bdf9ee3 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -268,13 +268,13 @@ struct system_device_crosststamp { }; /** - * struct system_counterval_t - system counter value with the pointer to the + * struct system_counterval_t - system counter value with the ID of the * corresponding clocksource * @cycles: System counter value - * @cs: Clocksource corresponding to system counter value. Used by - * timekeeping code to verify comparibility of two cycle values - * @cs_id: Clocksource ID corresponding to system counter value. To be - * used instead of cs in the future. + * @cs: Clocksource corresponding to system counter value. Timekeeping + * code now evaluates cs_id instead. + * @cs_id: Clocksource ID corresponding to system counter value. Used by + * timekeeping code to verify comparability of two cycle values. * The default ID, CSID_GENERIC, does not identify a specific * clocksource. */ diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 266d02809dbb1..0ff065c5d25b3 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1232,11 +1232,12 @@ int get_device_system_crosststamp(int (*get_time_fn) return ret; /* - * Verify that the clocksource associated with the captured - * system counter value is the same as the currently installed - * timekeeper clocksource + * Verify that the clocksource ID associated with the captured + * system counter value is the same as for the currently + * installed timekeeper clocksource */ - if (tk->tkr_mono.clock != system_counterval.cs) + if (system_counterval.cs_id == CSID_GENERIC || + tk->tkr_mono.clock->id != system_counterval.cs_id) return -ENODEV; cycles = system_counterval.cycles;