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dtrace: remove dead code for PR_REQUESTED

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libproc's PR_REQUESTED is not implemented on FreeBSD.  Remove dead code
in dtrace that would handle it.

Reviewed by:	markj
MFC after:	1 week
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D41225
This commit is contained in:
Eric van Gyzen 2023-07-27 17:06:33 -05:00
parent be1dd8e65b
commit 1112883e19
2 changed files with 1 additions and 96 deletions
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95
cddl/contrib/opensolaris/lib/libdtrace/common/dt_proc.c
View file

@ -366,84 +366,6 @@ dt_proc_attach(dt_proc_t *dpr, int exec)
}
}
/*
* Wait for a stopped process to be set running again by some other debugger.
* This is typically not required by /proc-based debuggers, since the usual
* model is that one debugger controls one victim. But DTrace, as usual, has
* its own needs: the stop() action assumes that prun(1) or some other tool
* will be applied to resume the victim process. This could be solved by
* adding a PCWRUN directive to /proc, but that seems like overkill unless
* other debuggers end up needing this functionality, so we implement a cheap
* equivalent to PCWRUN using the set of existing kernel mechanisms.
*
* Our intent is really not just to wait for the victim to run, but rather to
* wait for it to run and then stop again for a reason other than the current
* PR_REQUESTED stop. Since PCWSTOP/Pstopstatus() can be applied repeatedly
* to a stopped process and will return the same result without affecting the
* victim, we can just perform these operations repeatedly until Pstate()
* changes, the representative LWP ID changes, or the stop timestamp advances.
* dt_proc_control() will then rediscover the new state and continue as usual.
* When the process is still stopped in the same exact state, we sleep for a
* brief interval before waiting again so as not to spin consuming CPU cycles.
*/
static void
dt_proc_waitrun(dt_proc_t *dpr)
{
printf("%s:%s(%d): not implemented\n", __FUNCTION__, __FILE__,
__LINE__);
#ifdef DOODAD
struct ps_prochandle *P = dpr->dpr_proc;
const lwpstatus_t *psp = &Pstatus(P)->pr_lwp;
int krflag = psp->pr_flags & (PR_KLC | PR_RLC);
timestruc_t tstamp = psp->pr_tstamp;
lwpid_t lwpid = psp->pr_lwpid;
const long wstop = PCWSTOP;
int pfd = Pctlfd(P);
assert(DT_MUTEX_HELD(&dpr->dpr_lock));
assert(psp->pr_flags & PR_STOPPED);
assert(Pstate(P) == PS_STOP);
/*
* While we are waiting for the victim to run, clear PR_KLC and PR_RLC
* so that if the libdtrace client is killed, the victim stays stopped.
* dt_proc_destroy() will also observe this and perform PRELEASE_HANG.
*/
(void) Punsetflags(P, krflag);
Psync(P);
(void) pthread_mutex_unlock(&dpr->dpr_lock);
while (!dpr->dpr_quit) {
if (write(pfd, &wstop, sizeof (wstop)) == -1 && errno == EINTR)
continue; /* check dpr_quit and continue waiting */
(void) pthread_mutex_lock(&dpr->dpr_lock);
(void) Pstopstatus(P, PCNULL, 0);
psp = &Pstatus(P)->pr_lwp;
/*
* If we've reached a new state, found a new representative, or
* the stop timestamp has changed, restore PR_KLC/PR_RLC to its
* original setting and then return with dpr_lock held.
*/
if (Pstate(P) != PS_STOP || psp->pr_lwpid != lwpid ||
bcmp(&psp->pr_tstamp, &tstamp, sizeof (tstamp)) != 0) {
(void) Psetflags(P, krflag);
Psync(P);
return;
}
(void) pthread_mutex_unlock(&dpr->dpr_lock);
(void) poll(NULL, 0, MILLISEC / 2);
}
(void) pthread_mutex_lock(&dpr->dpr_lock);
#endif
}
typedef struct dt_proc_control_data {
dtrace_hdl_t *dpcd_hdl; /* DTrace handle */
dt_proc_t *dpcd_proc; /* proccess to control */
@ -532,23 +454,6 @@ dt_proc_control(void *arg)
dt_dprintf("pid %d: proc stopped showing %d/%d\n",
pid, psp->pr_why, psp->pr_what);
/*
* If the process stops showing PR_REQUESTED, then the
* DTrace stop() action was applied to it or another
* debugging utility (e.g. pstop(1)) asked it to stop.
* In either case, the user's intention is for the
* process to remain stopped until another external
* mechanism (e.g. prun(1)) is applied. So instead of
* setting the process running ourself, we wait for
* someone else to do so. Once that happens, we return
* to our normal loop waiting for an event of interest.
*/
if (psp->pr_why == PR_REQUESTED) {
dt_proc_waitrun(dpr);
(void) pthread_mutex_unlock(&dpr->dpr_lock);
continue;
}
/*
* If the process stops showing one of the events that
* we are tracing, perform the appropriate response.

2
lib/libproc/libproc.h
View file

@ -111,7 +111,7 @@ typedef enum {
typedef struct lwpstatus {
int pr_why;
#define PR_REQUESTED 1
#define PR_REQUESTED 1 /* not implemented */
#define PR_FAULTED 2
#define PR_SYSENTRY 3
#define PR_SYSEXIT 4