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Use a per-thread variable for keeping state when a thread is processing

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a KTR log entry.  Any KTR requests made while working on an entry are
ignored/discarded to prevent recursion.  This is a better fix for the
hack to futz with the CPU mask and call getnanotime() if KTR_LOCK or
KTR_WITNESS was on.  It also covers the actual formatting of the log entry
including dumping it to the display which the earlier hacks did not.
This commit is contained in:
John Baldwin 2001-12-13 10:33:20 +00:00
parent f8daa5a649
commit 69e9495750
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=87793
2 changed files with 9 additions and 10 deletions
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18
sys/kern/kern_ktr.c
View File

@ -42,7 +42,7 @@
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/libkern.h>
#include <sys/pcpu.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/time.h>
@ -121,6 +121,7 @@ ktr_tracepoint(u_int mask, const char *format, u_long arg1, u_long arg2,
struct ktr_entry *entry;
int newindex, saveindex;
critical_t savecrit;
struct thread *td;
#ifdef KTR_EXTEND
va_list ap;
#endif
@ -129,27 +130,23 @@ ktr_tracepoint(u_int mask, const char *format, u_long arg1, u_long arg2,
return;
if ((ktr_mask & mask) == 0)
return;
td = curthread;
if (td->td_inktr)
return;
savecrit = critical_enter();
if (((1 << KTR_CPU) & ktr_cpumask) == 0) {
critical_exit(savecrit);
return;
}
atomic_clear_int(&ktr_cpumask, 1 << KTR_CPU);
td->td_inktr++;
do {
saveindex = ktr_idx;
newindex = (saveindex + 1) & (KTR_ENTRIES - 1);
} while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
entry = &ktr_buf[saveindex];
/*
* XXX: The ktr_cpumask atomic ops should make this unnecessary.
*/
if ((ktr_mask & (KTR_LOCK | KTR_WITNESS)) != 0)
getnanotime(&entry->ktr_tv);
else
nanotime(&entry->ktr_tv);
atomic_set_int(&ktr_cpumask, 1 << KTR_CPU);
entry->ktr_cpu = KTR_CPU;
critical_exit(savecrit);
nanotime(&entry->ktr_tv);
#ifdef KTR_EXTEND
entry->ktr_filename = filename;
entry->ktr_line = line;
@ -176,6 +173,7 @@ ktr_tracepoint(u_int mask, const char *format, u_long arg1, u_long arg2,
entry->ktr_parm5 = arg5;
entry->ktr_parm6 = arg6;
#endif
td->td_inktr--;
}
#ifdef DDB

1
sys/sys/proc.h
View File

@ -253,6 +253,7 @@ struct thread {
void *td_wchan; /* (j) Sleep address. */
const char *td_wmesg; /* (j) Reason for sleep. */
u_char td_lastcpu; /* (j) Last cpu we were on. */
u_char td_inktr; /* (k) Currently handling a KTR. */
short td_locks; /* (k) DEBUG: lockmgr count of locks */
struct mtx *td_blocked; /* (j) Mutex process is blocked on. */
struct ithd *td_ithd; /* (b) For interrupt threads only. */