Revision 9c29bcd189f4ab1644b7125713602532d0aefdb7 authored by Eric Dumazet on 21 September 2018, 22:27:48 UTC, committed by David S. Miller on 24 September 2018, 04:55:25 UTC
As diagnosed by Song Liu, ndo_poll_controller() can be very dangerous on loaded hosts, since the cpu calling ndo_poll_controller() might steal all NAPI contexts (for all RX/TX queues of the NIC). This capture can last for unlimited amount of time, since one cpu is generally not able to drain all the queues under load. mlx5 uses NAPI for TX completions, so we better let core networking stack call the napi->poll() to avoid the capture. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Saeed Mahameed <saeedm@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent a24b66c
ordered-events.c
// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <inttypes.h>
#include <linux/list.h>
#include <linux/compiler.h>
#include <linux/string.h>
#include "ordered-events.h"
#include "session.h"
#include "asm/bug.h"
#include "debug.h"
#define pr_N(n, fmt, ...) \
eprintf(n, debug_ordered_events, fmt, ##__VA_ARGS__)
#define pr(fmt, ...) pr_N(1, pr_fmt(fmt), ##__VA_ARGS__)
static void queue_event(struct ordered_events *oe, struct ordered_event *new)
{
struct ordered_event *last = oe->last;
u64 timestamp = new->timestamp;
struct list_head *p;
++oe->nr_events;
oe->last = new;
pr_oe_time2(timestamp, "queue_event nr_events %u\n", oe->nr_events);
if (!last) {
list_add(&new->list, &oe->events);
oe->max_timestamp = timestamp;
return;
}
/*
* last event might point to some random place in the list as it's
* the last queued event. We expect that the new event is close to
* this.
*/
if (last->timestamp <= timestamp) {
while (last->timestamp <= timestamp) {
p = last->list.next;
if (p == &oe->events) {
list_add_tail(&new->list, &oe->events);
oe->max_timestamp = timestamp;
return;
}
last = list_entry(p, struct ordered_event, list);
}
list_add_tail(&new->list, &last->list);
} else {
while (last->timestamp > timestamp) {
p = last->list.prev;
if (p == &oe->events) {
list_add(&new->list, &oe->events);
return;
}
last = list_entry(p, struct ordered_event, list);
}
list_add(&new->list, &last->list);
}
}
static union perf_event *__dup_event(struct ordered_events *oe,
union perf_event *event)
{
union perf_event *new_event = NULL;
if (oe->cur_alloc_size < oe->max_alloc_size) {
new_event = memdup(event, event->header.size);
if (new_event)
oe->cur_alloc_size += event->header.size;
}
return new_event;
}
static union perf_event *dup_event(struct ordered_events *oe,
union perf_event *event)
{
return oe->copy_on_queue ? __dup_event(oe, event) : event;
}
static void free_dup_event(struct ordered_events *oe, union perf_event *event)
{
if (event && oe->copy_on_queue) {
oe->cur_alloc_size -= event->header.size;
free(event);
}
}
#define MAX_SAMPLE_BUFFER (64 * 1024 / sizeof(struct ordered_event))
static struct ordered_event *alloc_event(struct ordered_events *oe,
union perf_event *event)
{
struct list_head *cache = &oe->cache;
struct ordered_event *new = NULL;
union perf_event *new_event;
new_event = dup_event(oe, event);
if (!new_event)
return NULL;
if (!list_empty(cache)) {
new = list_entry(cache->next, struct ordered_event, list);
list_del(&new->list);
} else if (oe->buffer) {
new = oe->buffer + oe->buffer_idx;
if (++oe->buffer_idx == MAX_SAMPLE_BUFFER)
oe->buffer = NULL;
} else if (oe->cur_alloc_size < oe->max_alloc_size) {
size_t size = MAX_SAMPLE_BUFFER * sizeof(*new);
oe->buffer = malloc(size);
if (!oe->buffer) {
free_dup_event(oe, new_event);
return NULL;
}
pr("alloc size %" PRIu64 "B (+%zu), max %" PRIu64 "B\n",
oe->cur_alloc_size, size, oe->max_alloc_size);
oe->cur_alloc_size += size;
list_add(&oe->buffer->list, &oe->to_free);
/* First entry is abused to maintain the to_free list. */
oe->buffer_idx = 2;
new = oe->buffer + 1;
} else {
pr("allocation limit reached %" PRIu64 "B\n", oe->max_alloc_size);
}
new->event = new_event;
return new;
}
static struct ordered_event *
ordered_events__new_event(struct ordered_events *oe, u64 timestamp,
union perf_event *event)
{
struct ordered_event *new;
new = alloc_event(oe, event);
if (new) {
new->timestamp = timestamp;
queue_event(oe, new);
}
return new;
}
void ordered_events__delete(struct ordered_events *oe, struct ordered_event *event)
{
list_move(&event->list, &oe->cache);
oe->nr_events--;
free_dup_event(oe, event->event);
event->event = NULL;
}
int ordered_events__queue(struct ordered_events *oe, union perf_event *event,
u64 timestamp, u64 file_offset)
{
struct ordered_event *oevent;
if (!timestamp || timestamp == ~0ULL)
return -ETIME;
if (timestamp < oe->last_flush) {
pr_oe_time(timestamp, "out of order event\n");
pr_oe_time(oe->last_flush, "last flush, last_flush_type %d\n",
oe->last_flush_type);
oe->nr_unordered_events++;
}
oevent = ordered_events__new_event(oe, timestamp, event);
if (!oevent) {
ordered_events__flush(oe, OE_FLUSH__HALF);
oevent = ordered_events__new_event(oe, timestamp, event);
}
if (!oevent)
return -ENOMEM;
oevent->file_offset = file_offset;
return 0;
}
static int __ordered_events__flush(struct ordered_events *oe)
{
struct list_head *head = &oe->events;
struct ordered_event *tmp, *iter;
u64 limit = oe->next_flush;
u64 last_ts = oe->last ? oe->last->timestamp : 0ULL;
bool show_progress = limit == ULLONG_MAX;
struct ui_progress prog;
int ret;
if (!limit)
return 0;
if (show_progress)
ui_progress__init(&prog, oe->nr_events, "Processing time ordered events...");
list_for_each_entry_safe(iter, tmp, head, list) {
if (session_done())
return 0;
if (iter->timestamp > limit)
break;
ret = oe->deliver(oe, iter);
if (ret)
return ret;
ordered_events__delete(oe, iter);
oe->last_flush = iter->timestamp;
if (show_progress)
ui_progress__update(&prog, 1);
}
if (list_empty(head))
oe->last = NULL;
else if (last_ts <= limit)
oe->last = list_entry(head->prev, struct ordered_event, list);
if (show_progress)
ui_progress__finish();
return 0;
}
int ordered_events__flush(struct ordered_events *oe, enum oe_flush how)
{
static const char * const str[] = {
"NONE",
"FINAL",
"ROUND",
"HALF ",
};
int err;
if (oe->nr_events == 0)
return 0;
switch (how) {
case OE_FLUSH__FINAL:
oe->next_flush = ULLONG_MAX;
break;
case OE_FLUSH__HALF:
{
struct ordered_event *first, *last;
struct list_head *head = &oe->events;
first = list_entry(head->next, struct ordered_event, list);
last = oe->last;
/* Warn if we are called before any event got allocated. */
if (WARN_ONCE(!last || list_empty(head), "empty queue"))
return 0;
oe->next_flush = first->timestamp;
oe->next_flush += (last->timestamp - first->timestamp) / 2;
break;
}
case OE_FLUSH__ROUND:
case OE_FLUSH__NONE:
default:
break;
};
pr_oe_time(oe->next_flush, "next_flush - ordered_events__flush PRE %s, nr_events %u\n",
str[how], oe->nr_events);
pr_oe_time(oe->max_timestamp, "max_timestamp\n");
err = __ordered_events__flush(oe);
if (!err) {
if (how == OE_FLUSH__ROUND)
oe->next_flush = oe->max_timestamp;
oe->last_flush_type = how;
}
pr_oe_time(oe->next_flush, "next_flush - ordered_events__flush POST %s, nr_events %u\n",
str[how], oe->nr_events);
pr_oe_time(oe->last_flush, "last_flush\n");
return err;
}
void ordered_events__init(struct ordered_events *oe, ordered_events__deliver_t deliver)
{
INIT_LIST_HEAD(&oe->events);
INIT_LIST_HEAD(&oe->cache);
INIT_LIST_HEAD(&oe->to_free);
oe->max_alloc_size = (u64) -1;
oe->cur_alloc_size = 0;
oe->deliver = deliver;
}
void ordered_events__free(struct ordered_events *oe)
{
while (!list_empty(&oe->to_free)) {
struct ordered_event *event;
event = list_entry(oe->to_free.next, struct ordered_event, list);
list_del(&event->list);
free_dup_event(oe, event->event);
free(event);
}
}
void ordered_events__reinit(struct ordered_events *oe)
{
ordered_events__deliver_t old_deliver = oe->deliver;
ordered_events__free(oe);
memset(oe, '\0', sizeof(*oe));
ordered_events__init(oe, old_deliver);
}
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