From b42975a154d2e4f1654d8220cf6c3d48d354352d Mon Sep 17 00:00:00 2001 From: bz Date: Fri, 6 Dec 2019 16:34:04 +0000 Subject: [PATCH] Improve EPOCH_TRACE Two changes to EPOCH_TRACE: (1) add a sysctl to surpress the backtrace from epoch_trace_report(). Sometimes the log line for the recursion is enough and the backtrace massively spams the console. (2) In order to be able to go without the backtrace do not only print where the previous occurance happened, but also where the current one happens. That way we have file:line information for both and can look at them without the need for getting line numbers from backtrace and a debugging tool. Reviewed by: glebius Sponsored by: Netflix (originally) Differential Revision: https://reviews.freebsd.org/D22641 --- sys/kern/subr_epoch.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/sys/kern/subr_epoch.c b/sys/kern/subr_epoch.c index 0b3d634901be..be2242144c20 100644 --- a/sys/kern/subr_epoch.c +++ b/sys/kern/subr_epoch.c @@ -169,6 +169,10 @@ RB_GENERATE_STATIC(stacktree, stackentry, se_node, stackentry_compare); static struct mtx epoch_stacks_lock; MTX_SYSINIT(epochstacks, &epoch_stacks_lock, "epoch_stacks", MTX_DEF); +static bool epoch_trace_stack_print = true; +SYSCTL_BOOL(_kern_epoch, OID_AUTO, trace_stack_print, CTLFLAG_RWTUN, + &epoch_trace_stack_print, 0, "Print stack traces on epoch reports"); + static void epoch_trace_report(const char *fmt, ...) __printflike(1, 2); static inline void epoch_trace_report(const char *fmt, ...) @@ -197,7 +201,8 @@ epoch_trace_report(const char *fmt, ...) va_start(ap, fmt); (void)vprintf(fmt, ap); va_end(ap); - stack_print_ddb(&se.se_stack); + if (epoch_trace_stack_print) + stack_print_ddb(&se.se_stack); } static inline void @@ -209,8 +214,9 @@ epoch_trace_enter(struct thread *td, epoch_t epoch, epoch_tracker_t et, SLIST_FOREACH(iet, &td->td_epochs, et_tlink) if (iet->et_epoch == epoch) epoch_trace_report("Recursively entering epoch %s " - "previously entered at %s:%d\n", - epoch->e_name, iet->et_file, iet->et_line); + "at %s:%d, previously entered at %s:%d\n", + epoch->e_name, file, line, + iet->et_file, iet->et_line); et->et_epoch = epoch; et->et_file = file; et->et_line = line; @@ -223,9 +229,10 @@ epoch_trace_exit(struct thread *td, epoch_t epoch, epoch_tracker_t et, { if (SLIST_FIRST(&td->td_epochs) != et) { - epoch_trace_report("Exiting epoch %s in a not nested order. " - "Most recently entered %s at %s:%d\n", + epoch_trace_report("Exiting epoch %s in a not nested order " + "at %s:%d. Most recently entered %s at %s:%d\n", epoch->e_name, + file, line, SLIST_FIRST(&td->td_epochs)->et_epoch->e_name, SLIST_FIRST(&td->td_epochs)->et_file, SLIST_FIRST(&td->td_epochs)->et_line);