The branch main has been updated by glebius: URL: https://cgit.FreeBSD.org/src/commit/?id=d96fccc50513b807c5ec5e880c2340c1efcb97c1
commit d96fccc50513b807c5ec5e880c2340c1efcb97c1 Author: Gleb Smirnoff <[email protected]> AuthorDate: 2021-12-02 18:59:43 +0000 Commit: Gleb Smirnoff <[email protected]> CommitDate: 2021-12-02 19:02:51 +0000 epoch: with EPOCH_TRACE add epoch_where_report() which will report where the epoch was entered and also mark the tracker, so that exit will also be reported. Helps to understand epoch entrance/exit scenarios in complex cases, like network stack. As everything else under EPOCH_TRACE it is a developer only tool. --- sys/kern/subr_epoch.c | 40 +++++++++++++++++++++++++++++++++------- sys/sys/epoch.h | 3 +++ 2 files changed, 36 insertions(+), 7 deletions(-) diff --git a/sys/kern/subr_epoch.c b/sys/kern/subr_epoch.c index 651fd8b419f0..74524fb3f97e 100644 --- a/sys/kern/subr_epoch.c +++ b/sys/kern/subr_epoch.c @@ -147,6 +147,13 @@ static struct sx epoch_sx; #define EPOCH_LOCK() sx_xlock(&epoch_sx) #define EPOCH_UNLOCK() sx_xunlock(&epoch_sx) +static epoch_record_t +epoch_currecord(epoch_t epoch) +{ + + return (zpcpu_get(epoch->e_pcpu_record)); +} + #ifdef EPOCH_TRACE struct stackentry { RB_ENTRY(stackentry) se_node; @@ -230,6 +237,7 @@ epoch_trace_enter(struct thread *td, epoch_t epoch, epoch_tracker_t et, et->et_epoch = epoch; et->et_file = file; et->et_line = line; + et->et_flags = 0; SLIST_INSERT_HEAD(&td->td_epochs, et, et_tlink); } @@ -250,6 +258,9 @@ epoch_trace_exit(struct thread *td, epoch_t epoch, epoch_tracker_t et, SLIST_REMOVE(&td->td_epochs, et, epoch_tracker, et_tlink); } else SLIST_REMOVE_HEAD(&td->td_epochs, et_tlink); + if (et->et_flags & ET_REPORT_EXIT) + printf("Td %p exiting epoch %s at %s:%d\n", td, epoch->e_name, + file, line); } /* Used by assertions that check thread state before going to sleep. */ @@ -262,6 +273,28 @@ epoch_trace_list(struct thread *td) printf("Epoch %s entered at %s:%d\n", iet->et_epoch->e_name, iet->et_file, iet->et_line); } + +void +epoch_where_report(epoch_t epoch) +{ + epoch_record_t er; + struct epoch_tracker *tdwait; + + MPASS(epoch != NULL); + MPASS((epoch->e_flags & EPOCH_PREEMPT) != 0); + MPASS(!THREAD_CAN_SLEEP()); + critical_enter(); + er = epoch_currecord(epoch); + TAILQ_FOREACH(tdwait, &er->er_tdlist, et_link) + if (tdwait->et_td == curthread) + break; + critical_exit(); + if (tdwait != NULL) { + tdwait->et_flags |= ET_REPORT_EXIT; + printf("Td %p entered epoch %s at %s:%d\n", curthread, + epoch->e_name, tdwait->et_file, tdwait->et_line); + } +} #endif /* EPOCH_TRACE */ static void @@ -422,13 +455,6 @@ epoch_free(epoch_t epoch) EPOCH_UNLOCK(); } -static epoch_record_t -epoch_currecord(epoch_t epoch) -{ - - return (zpcpu_get(epoch->e_pcpu_record)); -} - #define INIT_CHECK(epoch) \ do { \ if (__predict_false((epoch) == NULL)) \ diff --git a/sys/sys/epoch.h b/sys/sys/epoch.h index 85c791d3df6c..6ce0fcd01c60 100644 --- a/sys/sys/epoch.h +++ b/sys/sys/epoch.h @@ -61,6 +61,8 @@ struct epoch_tracker { SLIST_ENTRY(epoch_tracker) et_tlink; const char *et_file; int et_line; + int et_flags; +#define ET_REPORT_EXIT 0x1 #endif } __aligned(sizeof(void *)); typedef struct epoch_tracker *epoch_tracker_t; @@ -86,6 +88,7 @@ void _epoch_enter_preempt(epoch_t epoch, epoch_tracker_t et EPOCH_FILE_LINE); void _epoch_exit_preempt(epoch_t epoch, epoch_tracker_t et EPOCH_FILE_LINE); #ifdef EPOCH_TRACE void epoch_trace_list(struct thread *); +void epoch_where_report(epoch_t); #define epoch_enter_preempt(epoch, et) _epoch_enter_preempt(epoch, et, __FILE__, __LINE__) #define epoch_exit_preempt(epoch, et) _epoch_exit_preempt(epoch, et, __FILE__, __LINE__) #else
