From: Menglong Dong <[email protected]>
In the commit c504e5c2f964 ("net: skb: introduce kfree_skb_reason()")
drop reason is introduced to the tracepoint of kfree_skb. Therefore,
drop_monitor is able to report the drop reason to users by netlink.
The drop reasons are reported as string to users, which is exactly
the same as what we do when reporting it to ftrace.
Signed-off-by: Menglong Dong <[email protected]>
---
v6:
- check the range of drop reason in net_dm_packet_report_fill()
v5:
- check if drop reason larger than SKB_DROP_REASON_MAX
v4:
- report drop reasons as string
v3:
- referring to cb->reason and cb->pc directly in
net_dm_packet_report_fill()
v2:
- get a pointer to struct net_dm_skb_cb instead of local var for
each field
---
include/uapi/linux/net_dropmon.h | 1 +
net/core/drop_monitor.c | 29 +++++++++++++++++++++++++----
2 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/include/uapi/linux/net_dropmon.h b/include/uapi/linux/net_dropmon.h
index 66048cc5d7b3..1bbea8f0681e 100644
--- a/include/uapi/linux/net_dropmon.h
+++ b/include/uapi/linux/net_dropmon.h
@@ -93,6 +93,7 @@ enum net_dm_attr {
NET_DM_ATTR_SW_DROPS, /* flag */
NET_DM_ATTR_HW_DROPS, /* flag */
NET_DM_ATTR_FLOW_ACTION_COOKIE, /* binary */
+ NET_DM_ATTR_REASON, /* string */
__NET_DM_ATTR_MAX,
NET_DM_ATTR_MAX = __NET_DM_ATTR_MAX - 1
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 7b288a121a41..1180f1a28599 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -48,6 +48,16 @@
static int trace_state = TRACE_OFF;
static bool monitor_hw;
+#undef EM
+#undef EMe
+
+#define EM(a, b) [a] = #b,
+#define EMe(a, b) [a] = #b
+
+static const char *drop_reasons[SKB_DROP_REASON_MAX + 1] = {
+ TRACE_SKB_DROP_REASON
+};
+
/* net_dm_mutex
*
* An overall lock guarding every operation coming from userspace.
@@ -126,6 +136,7 @@ struct net_dm_skb_cb {
struct devlink_trap_metadata *hw_metadata;
void *pc;
};
+ enum skb_drop_reason reason;
};
#define NET_DM_SKB_CB(__skb) ((struct net_dm_skb_cb *)&((__skb)->cb[0]))
@@ -498,6 +509,7 @@ static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
{
ktime_t tstamp = ktime_get_real();
struct per_cpu_dm_data *data;
+ struct net_dm_skb_cb *cb;
struct sk_buff *nskb;
unsigned long flags;
@@ -508,7 +520,9 @@ static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
if (!nskb)
return;
- NET_DM_SKB_CB(nskb)->pc = location;
+ cb = NET_DM_SKB_CB(nskb);
+ cb->reason = reason;
+ cb->pc = location;
/* Override the timestamp because we care about the time when the
* packet was dropped.
*/
@@ -606,8 +620,9 @@ static int net_dm_packet_report_in_port_put(struct sk_buff *msg, int ifindex,
static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
size_t payload_len)
{
- u64 pc = (u64)(uintptr_t) NET_DM_SKB_CB(skb)->pc;
+ struct net_dm_skb_cb *cb = NET_DM_SKB_CB(skb);
char buf[NET_DM_MAX_SYMBOL_LEN];
+ unsigned int reason;
struct nlattr *attr;
void *hdr;
int rc;
@@ -620,10 +635,16 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
if (nla_put_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_SW))
goto nla_put_failure;
- if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, pc, NET_DM_ATTR_PAD))
+ if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, (u64)(uintptr_t)cb->pc,
+ NET_DM_ATTR_PAD))
+ goto nla_put_failure;
+
+ reason = (unsigned int)cb->reason;
+ if (reason < SKB_DROP_REASON_MAX &&
+ nla_put_string(msg, NET_DM_ATTR_REASON, drop_reasons[reason]))
goto nla_put_failure;
- snprintf(buf, sizeof(buf), "%pS", NET_DM_SKB_CB(skb)->pc);
+ snprintf(buf, sizeof(buf), "%pS", cb->pc);
if (nla_put_string(msg, NET_DM_ATTR_SYMBOL, buf))
goto nla_put_failure;
--
2.27.0
On Sat, Feb 05, 2022 at 04:17:38PM +0800, [email protected] wrote:
> diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
> index 7b288a121a41..1180f1a28599 100644
> --- a/net/core/drop_monitor.c
> +++ b/net/core/drop_monitor.c
> @@ -48,6 +48,16 @@
> static int trace_state = TRACE_OFF;
> static bool monitor_hw;
>
> +#undef EM
> +#undef EMe
> +
> +#define EM(a, b) [a] = #b,
> +#define EMe(a, b) [a] = #b
> +
> +static const char *drop_reasons[SKB_DROP_REASON_MAX + 1] = {
> + TRACE_SKB_DROP_REASON
> +};
> +
> /* net_dm_mutex
> *
> * An overall lock guarding every operation coming from userspace.
> @@ -126,6 +136,7 @@ struct net_dm_skb_cb {
> struct devlink_trap_metadata *hw_metadata;
> void *pc;
> };
> + enum skb_drop_reason reason;
> };
>
> #define NET_DM_SKB_CB(__skb) ((struct net_dm_skb_cb *)&((__skb)->cb[0]))
> @@ -498,6 +509,7 @@ static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
> {
> ktime_t tstamp = ktime_get_real();
> struct per_cpu_dm_data *data;
> + struct net_dm_skb_cb *cb;
> struct sk_buff *nskb;
> unsigned long flags;
>
> @@ -508,7 +520,9 @@ static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
> if (!nskb)
> return;
>
> - NET_DM_SKB_CB(nskb)->pc = location;
> + cb = NET_DM_SKB_CB(nskb);
> + cb->reason = reason;
> + cb->pc = location;
> /* Override the timestamp because we care about the time when the
> * packet was dropped.
> */
> @@ -606,8 +620,9 @@ static int net_dm_packet_report_in_port_put(struct sk_buff *msg, int ifindex,
> static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
> size_t payload_len)
> {
> - u64 pc = (u64)(uintptr_t) NET_DM_SKB_CB(skb)->pc;
> + struct net_dm_skb_cb *cb = NET_DM_SKB_CB(skb);
> char buf[NET_DM_MAX_SYMBOL_LEN];
> + unsigned int reason;
> struct nlattr *attr;
> void *hdr;
> int rc;
> @@ -620,10 +635,16 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
> if (nla_put_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_SW))
> goto nla_put_failure;
>
> - if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, pc, NET_DM_ATTR_PAD))
> + if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, (u64)(uintptr_t)cb->pc,
> + NET_DM_ATTR_PAD))
> + goto nla_put_failure;
> +
> + reason = (unsigned int)cb->reason;
> + if (reason < SKB_DROP_REASON_MAX &&
> + nla_put_string(msg, NET_DM_ATTR_REASON, drop_reasons[reason]))
You need to make sure 'msg' has enough room for this attribute. Account
for it in net_dm_packet_report_size()
> goto nla_put_failure;
>
> - snprintf(buf, sizeof(buf), "%pS", NET_DM_SKB_CB(skb)->pc);
> + snprintf(buf, sizeof(buf), "%pS", cb->pc);
> if (nla_put_string(msg, NET_DM_ATTR_SYMBOL, buf))
> goto nla_put_failure;
>
> --
> 2.27.0
>
On Sat, 5 Feb 2022 16:17:38 +0800
[email protected] wrote:
> --- a/net/core/drop_monitor.c
> +++ b/net/core/drop_monitor.c
> @@ -48,6 +48,16 @@
> static int trace_state = TRACE_OFF;
> static bool monitor_hw;
>
> +#undef EM
> +#undef EMe
> +
> +#define EM(a, b) [a] = #b,
> +#define EMe(a, b) [a] = #b
> +
> +static const char *drop_reasons[SKB_DROP_REASON_MAX + 1] = {
Do you need to define the size above? Can't the compiler do it for you?
static const char *drop_reasons[] = {
-- Steve
> + TRACE_SKB_DROP_REASON
> +};
> +
> /* net_dm_mutex
> *
On Mon, Feb 7, 2022 at 10:43 PM Steven Rostedt <[email protected]> wrote:
>
> On Sat, 5 Feb 2022 16:17:38 +0800
> [email protected] wrote:
>
> > --- a/net/core/drop_monitor.c
> > +++ b/net/core/drop_monitor.c
> > @@ -48,6 +48,16 @@
> > static int trace_state = TRACE_OFF;
> > static bool monitor_hw;
> >
> > +#undef EM
> > +#undef EMe
> > +
> > +#define EM(a, b) [a] = #b,
> > +#define EMe(a, b) [a] = #b
> > +
> > +static const char *drop_reasons[SKB_DROP_REASON_MAX + 1] = {
>
> Do you need to define the size above? Can't the compiler do it for you?
>
> static const char *drop_reasons[] = {
>
Yeah, it seems the compiler can do this job. Thanks!
> -- Steve
>
> > + TRACE_SKB_DROP_REASON
> > +};
> > +
> > /* net_dm_mutex
> > *
On Sun, Feb 6, 2022 at 7:26 PM Ido Schimmel <[email protected]> wrote:
>
> On Sat, Feb 05, 2022 at 04:17:38PM +0800, [email protected] wrote:
> > diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
> > index 7b288a121a41..1180f1a28599 100644
> > --- a/net/core/drop_monitor.c
> > +++ b/net/core/drop_monitor.c
> > @@ -48,6 +48,16 @@
> > static int trace_state = TRACE_OFF;
> > static bool monitor_hw;
> >
> > +#undef EM
> > +#undef EMe
> > +
> > +#define EM(a, b) [a] = #b,
> > +#define EMe(a, b) [a] = #b
> > +
> > +static const char *drop_reasons[SKB_DROP_REASON_MAX + 1] = {
> > + TRACE_SKB_DROP_REASON
> > +};
> > +
> > /* net_dm_mutex
> > *
> > * An overall lock guarding every operation coming from userspace.
> > @@ -126,6 +136,7 @@ struct net_dm_skb_cb {
> > struct devlink_trap_metadata *hw_metadata;
> > void *pc;
> > };
> > + enum skb_drop_reason reason;
> > };
> >
> > #define NET_DM_SKB_CB(__skb) ((struct net_dm_skb_cb *)&((__skb)->cb[0]))
> > @@ -498,6 +509,7 @@ static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
> > {
> > ktime_t tstamp = ktime_get_real();
> > struct per_cpu_dm_data *data;
> > + struct net_dm_skb_cb *cb;
> > struct sk_buff *nskb;
> > unsigned long flags;
> >
> > @@ -508,7 +520,9 @@ static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
> > if (!nskb)
> > return;
> >
> > - NET_DM_SKB_CB(nskb)->pc = location;
> > + cb = NET_DM_SKB_CB(nskb);
> > + cb->reason = reason;
> > + cb->pc = location;
> > /* Override the timestamp because we care about the time when the
> > * packet was dropped.
> > */
> > @@ -606,8 +620,9 @@ static int net_dm_packet_report_in_port_put(struct sk_buff *msg, int ifindex,
> > static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
> > size_t payload_len)
> > {
> > - u64 pc = (u64)(uintptr_t) NET_DM_SKB_CB(skb)->pc;
> > + struct net_dm_skb_cb *cb = NET_DM_SKB_CB(skb);
> > char buf[NET_DM_MAX_SYMBOL_LEN];
> > + unsigned int reason;
> > struct nlattr *attr;
> > void *hdr;
> > int rc;
> > @@ -620,10 +635,16 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
> > if (nla_put_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_SW))
> > goto nla_put_failure;
> >
> > - if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, pc, NET_DM_ATTR_PAD))
> > + if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, (u64)(uintptr_t)cb->pc,
> > + NET_DM_ATTR_PAD))
> > + goto nla_put_failure;
> > +
> > + reason = (unsigned int)cb->reason;
> > + if (reason < SKB_DROP_REASON_MAX &&
> > + nla_put_string(msg, NET_DM_ATTR_REASON, drop_reasons[reason]))
>
> You need to make sure 'msg' has enough room for this attribute. Account
> for it in net_dm_packet_report_size()
>
Ok, I see what you mean now, thanks!
> > goto nla_put_failure;
> >
> > - snprintf(buf, sizeof(buf), "%pS", NET_DM_SKB_CB(skb)->pc);
> > + snprintf(buf, sizeof(buf), "%pS", cb->pc);
> > if (nla_put_string(msg, NET_DM_ATTR_SYMBOL, buf))
> > goto nla_put_failure;
> >
> > --
> > 2.27.0
> >