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Fix assertion failures on FreeBSD due to kevent() returning multiple …
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…entries for the same file event source.

Maintain linked lists of all returned events for each event source, instead of supporting just a single event per event source.
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@ambrop72
ambrop72 committed Jan 10, 2016
1 parent 4b76199 commit fac69ce
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Showing 2 changed files with 40 additions and 26 deletions.
61 changes: 37 additions & 24 deletions system/BReactor_badvpn.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -193,20 +193,21 @@ static void set_kevent_fd_pointers (BReactor *bsys)
for (int i = 0; i < bsys->kevent_results_num; i++) {
struct kevent *event = &bsys->kevent_results[i];
ASSERT(event->udata)

int *tag = event->udata;
switch (*tag) {
case KEVENT_TAG_FD: {
BFileDescriptor *bfd = UPPER_OBJECT(tag, BFileDescriptor, kevent_tag);
ASSERT(bfd->active)
ASSERT(!bfd->kevent_returned_ptr)
bfd->kevent_returned_ptr = (int **)&event->udata;
bsys->kevent_prev_event[i] = bfd->kevent_last_event;
bfd->kevent_last_event = i;
} break;

case KEVENT_TAG_KEVENT: {
BReactorKEvent *kev = UPPER_OBJECT(tag, BReactorKEvent, kevent_tag);
ASSERT(kev->reactor == bsys)
ASSERT(!kev->kevent_returned_ptr)
kev->kevent_returned_ptr = (int **)&event->udata;
bsys->kevent_prev_event[i] = kev->kevent_last_event;
kev->kevent_last_event = i;
} break;

default:
Expand Down Expand Up @@ -873,7 +874,8 @@ int BReactor_Exec (BReactor *bsys)
// dispatch kevent
if (bsys->kevent_results_pos < bsys->kevent_results_num) {
// grab event
struct kevent *event = &bsys->kevent_results[bsys->kevent_results_pos];
int event_index = bsys->kevent_results_pos;
struct kevent *event = &bsys->kevent_results[event_index];
bsys->kevent_results_pos++;

// check if the event was removed
Expand All @@ -888,10 +890,11 @@ int BReactor_Exec (BReactor *bsys)
// get BFileDescriptor
BFileDescriptor *bfd = UPPER_OBJECT(tag, BFileDescriptor, kevent_tag);
ASSERT(bfd->active)
ASSERT(bfd->kevent_returned_ptr == (int **)&event->udata)

// zero pointer to the kevent entry
bfd->kevent_returned_ptr = NULL;
// when we get to the last event for this fd, reset kevent_last_event
if (event_index == bfd->kevent_last_event) {
bfd->kevent_last_event = -1;
}

// calculate event to report
int events = 0;
Expand All @@ -917,10 +920,11 @@ int BReactor_Exec (BReactor *bsys)
// get BReactorKEvent
BReactorKEvent *kev = UPPER_OBJECT(tag, BReactorKEvent, kevent_tag);
ASSERT(kev->reactor == bsys)
ASSERT(kev->kevent_returned_ptr == (int **)&event->udata)

// zero pointer to the kevent entry
kev->kevent_returned_ptr = NULL;
// when we get to the last event for this fd, reset kevent_last_event
if (event_index == kev->kevent_last_event) {
kev->kevent_last_event = -1;
}

// call handler
BLog(BLOG_DEBUG, "Dispatching kevent");
Expand Down Expand Up @@ -1109,8 +1113,8 @@ int BReactor_AddFileDescriptor (BReactor *bsys, BFileDescriptor *bs)
// set kevent tag
bs->kevent_tag = KEVENT_TAG_FD;

// set kevent returned pointer
bs->kevent_returned_ptr = NULL;
// have no events
bs->kevent_last_event = -1;

#endif

Expand Down Expand Up @@ -1163,9 +1167,13 @@ void BReactor_RemoveFileDescriptor (BReactor *bsys, BFileDescriptor *bs)
// delete kevents
update_kevent_fd_events(bsys, bs, 0);

// write through kevent returned pointer
if (bs->kevent_returned_ptr) {
*bs->kevent_returned_ptr = NULL;
// invalidate any events
int event_index = bs->kevent_last_event;
while (event_index != -1) {
ASSERT(event_index >= 0 && event_index < bsys->kevent_results_num)
struct kevent *event = &bsys->kevent_results[event_index];
event->udata = NULL;
event_index = bsys->kevent_prev_event[event_index];
}

#endif
Expand Down Expand Up @@ -1316,8 +1324,8 @@ int BReactorKEvent_Init (BReactorKEvent *o, BReactor *reactor, BReactorKEvent_ha
// set kevent tag
o->kevent_tag = KEVENT_TAG_KEVENT;

// set kevent returned pointer
o->kevent_returned_ptr = NULL;
// have no events
o->kevent_last_event = -1;

DebugObject_Init(&o->d_obj);
DebugCounter_Increment(&o->reactor->d_kevent_ctr);
Expand All @@ -1326,12 +1334,17 @@ int BReactorKEvent_Init (BReactorKEvent *o, BReactor *reactor, BReactorKEvent_ha

void BReactorKEvent_Free (BReactorKEvent *o)
{
BReactor *reactor = o->reactor;
DebugObject_Free(&o->d_obj);
DebugCounter_Decrement(&o->reactor->d_kevent_ctr);

// write through kevent returned pointer
if (o->kevent_returned_ptr) {
*o->kevent_returned_ptr = NULL;
DebugCounter_Decrement(&reactor->d_kevent_ctr);

// invalidate any events
int event_index = o->kevent_last_event;
while (event_index != -1) {
ASSERT(event_index >= 0 && event_index < reactor->kevent_results_num)
struct kevent *event = &reactor->kevent_results[event_index];
event->udata = NULL;
event_index = reactor->kevent_prev_event[event_index];
}

// delete kevent
Expand All @@ -1340,7 +1353,7 @@ void BReactorKEvent_Free (BReactorKEvent *o)
event.ident = o->ident;
event.filter = o->filter;
event.flags = EV_DELETE;
ASSERT_FORCE(kevent(o->reactor->kqueue_fd, &event, 1, NULL, 0, NULL) == 0)
ASSERT_FORCE(kevent(reactor->kqueue_fd, &event, 1, NULL, 0, NULL) == 0)
}

#endif
Expand Down
5 changes: 3 additions & 2 deletions system/BReactor_badvpn.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -203,7 +203,7 @@ typedef struct BFileDescriptor_t {

#ifdef BADVPN_USE_KEVENT
int kevent_tag;
int **kevent_returned_ptr;
int kevent_last_event;
#endif

#ifdef BADVPN_USE_POLL
Expand Down Expand Up @@ -265,6 +265,7 @@ typedef struct {
#ifdef BADVPN_USE_KEVENT
int kqueue_fd;
struct kevent kevent_results[BSYSTEM_MAX_RESULTS];
int kevent_prev_event[BSYSTEM_MAX_RESULTS];
int kevent_results_num;
int kevent_results_pos;
#endif
Expand Down Expand Up @@ -531,7 +532,7 @@ typedef struct {
uintptr_t ident;
short filter;
int kevent_tag;
int **kevent_returned_ptr;
int kevent_last_event;
DebugObject d_obj;
} BReactorKEvent;

Expand Down

1 comment on commit fac69ce

@ambrop72
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This changes lead to crashing on (ARM) android

Hey, I don't think that's possible because the kevent code is not used on Android (Android is Linux so it should use the epoll code).

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