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
strbuf.c
// SPDX-License-Identifier: GPL-2.0
#include "debug.h"
#include "util.h"
#include <linux/kernel.h>
#include <errno.h>
/*
* Used as the default ->buf value, so that people can always assume
* buf is non NULL and ->buf is NUL terminated even for a freshly
* initialized strbuf.
*/
char strbuf_slopbuf[1];
int strbuf_init(struct strbuf *sb, ssize_t hint)
{
sb->alloc = sb->len = 0;
sb->buf = strbuf_slopbuf;
if (hint)
return strbuf_grow(sb, hint);
return 0;
}
void strbuf_release(struct strbuf *sb)
{
if (sb->alloc) {
zfree(&sb->buf);
strbuf_init(sb, 0);
}
}
char *strbuf_detach(struct strbuf *sb, size_t *sz)
{
char *res = sb->alloc ? sb->buf : NULL;
if (sz)
*sz = sb->len;
strbuf_init(sb, 0);
return res;
}
int strbuf_grow(struct strbuf *sb, size_t extra)
{
char *buf;
size_t nr = sb->len + extra + 1;
if (nr < sb->alloc)
return 0;
if (nr <= sb->len)
return -E2BIG;
if (alloc_nr(sb->alloc) > nr)
nr = alloc_nr(sb->alloc);
/*
* Note that sb->buf == strbuf_slopbuf if sb->alloc == 0, and it is
* a static variable. Thus we have to avoid passing it to realloc.
*/
buf = realloc(sb->alloc ? sb->buf : NULL, nr * sizeof(*buf));
if (!buf)
return -ENOMEM;
sb->buf = buf;
sb->alloc = nr;
return 0;
}
int strbuf_addch(struct strbuf *sb, int c)
{
int ret = strbuf_grow(sb, 1);
if (ret)
return ret;
sb->buf[sb->len++] = c;
sb->buf[sb->len] = '\0';
return 0;
}
int strbuf_add(struct strbuf *sb, const void *data, size_t len)
{
int ret = strbuf_grow(sb, len);
if (ret)
return ret;
memcpy(sb->buf + sb->len, data, len);
return strbuf_setlen(sb, sb->len + len);
}
static int strbuf_addv(struct strbuf *sb, const char *fmt, va_list ap)
{
int len, ret;
va_list ap_saved;
if (!strbuf_avail(sb)) {
ret = strbuf_grow(sb, 64);
if (ret)
return ret;
}
va_copy(ap_saved, ap);
len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
if (len < 0)
return len;
if (len > strbuf_avail(sb)) {
ret = strbuf_grow(sb, len);
if (ret)
return ret;
len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap_saved);
va_end(ap_saved);
if (len > strbuf_avail(sb)) {
pr_debug("this should not happen, your vsnprintf is broken");
return -EINVAL;
}
}
return strbuf_setlen(sb, sb->len + len);
}
int strbuf_addf(struct strbuf *sb, const char *fmt, ...)
{
va_list ap;
int ret;
va_start(ap, fmt);
ret = strbuf_addv(sb, fmt, ap);
va_end(ap);
return ret;
}
ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint)
{
size_t oldlen = sb->len;
size_t oldalloc = sb->alloc;
int ret;
ret = strbuf_grow(sb, hint ? hint : 8192);
if (ret)
return ret;
for (;;) {
ssize_t cnt;
cnt = read(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
if (cnt < 0) {
if (oldalloc == 0)
strbuf_release(sb);
else
strbuf_setlen(sb, oldlen);
return cnt;
}
if (!cnt)
break;
sb->len += cnt;
ret = strbuf_grow(sb, 8192);
if (ret)
return ret;
}
sb->buf[sb->len] = '\0';
return sb->len - oldlen;
}
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