Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 465 insertions, 0 deletions

diff --git a/include/net/red.h b/include/net/red.h
new file mode 100644
index 000000000..159a09359
--- /dev/null
+++ b/include/net/red.h
@@ -0,0 +1,465 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_SCHED_RED_H
+#define __NET_SCHED_RED_H
+
+#include <linux/types.h>
+#include <linux/bug.h>
+#include <net/pkt_sched.h>
+#include <net/inet_ecn.h>
+#include <net/dsfield.h>
+#include <linux/reciprocal_div.h>
+
+/*	Random Early Detection (RED) algorithm.
+	=======================================
+
+	Source: Sally Floyd and Van Jacobson, "Random Early Detection Gateways
+	for Congestion Avoidance", 1993, IEEE/ACM Transactions on Networking.
+
+	This file codes a "divisionless" version of RED algorithm
+	as written down in Fig.17 of the paper.
+
+	Short description.
+	------------------
+
+	When a new packet arrives we calculate the average queue length:
+
+	avg = (1-W)*avg + W*current_queue_len,
+
+	W is the filter time constant (chosen as 2^(-Wlog)), it controls
+	the inertia of the algorithm. To allow larger bursts, W should be
+	decreased.
+
+	if (avg > th_max) -> packet marked (dropped).
+	if (avg < th_min) -> packet passes.
+	if (th_min < avg < th_max) we calculate probability:
+
+	Pb = max_P * (avg - th_min)/(th_max-th_min)
+
+	and mark (drop) packet with this probability.
+	Pb changes from 0 (at avg==th_min) to max_P (avg==th_max).
+	max_P should be small (not 1), usually 0.01..0.02 is good value.
+
+	max_P is chosen as a number, so that max_P/(th_max-th_min)
+	is a negative power of two in order arithmetic to contain
+	only shifts.
+
+
+	Parameters, settable by user:
+	-----------------------------
+
+	qth_min		- bytes (should be < qth_max/2)
+	qth_max		- bytes (should be at least 2*qth_min and less limit)
+	Wlog	       	- bits (<32) log(1/W).
+	Plog	       	- bits (<32)
+
+	Plog is related to max_P by formula:
+
+	max_P = (qth_max-qth_min)/2^Plog;
+
+	F.e. if qth_max=128K and qth_min=32K, then Plog=22
+	corresponds to max_P=0.02
+
+	Scell_log
+	Stab
+
+	Lookup table for log((1-W)^(t/t_ave).
+
+
+	NOTES:
+
+	Upper bound on W.
+	-----------------
+
+	If you want to allow bursts of L packets of size S,
+	you should choose W:
+
+	L + 1 - th_min/S < (1-(1-W)^L)/W
+
+	th_min/S = 32         th_min/S = 4
+
+	log(W)	L
+	-1	33
+	-2	35
+	-3	39
+	-4	46
+	-5	57
+	-6	75
+	-7	101
+	-8	135
+	-9	190
+	etc.
+ */
+
+/*
+ * Adaptative RED : An Algorithm for Increasing the Robustness of RED's AQM
+ * (Sally FLoyd, Ramakrishna Gummadi, and Scott Shenker) August 2001
+ *
+ * Every 500 ms:
+ *  if (avg > target and max_p <= 0.5)
+ *   increase max_p : max_p += alpha;
+ *  else if (avg < target and max_p >= 0.01)
+ *   decrease max_p : max_p *= beta;
+ *
+ * target :[qth_min + 0.4*(qth_min - qth_max),
+ *          qth_min + 0.6*(qth_min - qth_max)].
+ * alpha : min(0.01, max_p / 4)
+ * beta : 0.9
+ * max_P is a Q0.32 fixed point number (with 32 bits mantissa)
+ * max_P between 0.01 and 0.5 (1% - 50%) [ Its no longer a negative power of two ]
+ */
+#define RED_ONE_PERCENT ((u32)DIV_ROUND_CLOSEST(1ULL<<32, 100))
+
+#define MAX_P_MIN (1 * RED_ONE_PERCENT)
+#define MAX_P_MAX (50 * RED_ONE_PERCENT)
+#define MAX_P_ALPHA(val) min(MAX_P_MIN, val / 4)
+
+#define RED_STAB_SIZE	256
+#define RED_STAB_MASK	(RED_STAB_SIZE - 1)
+
+struct red_stats {
+	u32		prob_drop;	/* Early probability drops */
+	u32		prob_mark;	/* Early probability marks */
+	u32		forced_drop;	/* Forced drops, qavg > max_thresh */
+	u32		forced_mark;	/* Forced marks, qavg > max_thresh */
+	u32		pdrop;          /* Drops due to queue limits */
+};
+
+struct red_parms {
+	/* Parameters */
+	u32		qth_min;	/* Min avg length threshold: Wlog scaled */
+	u32		qth_max;	/* Max avg length threshold: Wlog scaled */
+	u32		Scell_max;
+	u32		max_P;		/* probability, [0 .. 1.0] 32 scaled */
+	/* reciprocal_value(max_P / qth_delta) */
+	struct reciprocal_value	max_P_reciprocal;
+	u32		qth_delta;	/* max_th - min_th */
+	u32		target_min;	/* min_th + 0.4*(max_th - min_th) */
+	u32		target_max;	/* min_th + 0.6*(max_th - min_th) */
+	u8		Scell_log;
+	u8		Wlog;		/* log(W)		*/
+	u8		Plog;		/* random number bits	*/
+	u8		Stab[RED_STAB_SIZE];
+};
+
+struct red_vars {
+	/* Variables */
+	int		qcount;		/* Number of packets since last random
+					   number generation */
+	u32		qR;		/* Cached random number */
+
+	unsigned long	qavg;		/* Average queue length: Wlog scaled */
+	ktime_t		qidlestart;	/* Start of current idle period */
+};
+
+static inline u32 red_maxp(u8 Plog)
+{
+	return Plog < 32 ? (~0U >> Plog) : ~0U;
+}
+
+static inline void red_set_vars(struct red_vars *v)
+{
+	/* Reset average queue length, the value is strictly bound
+	 * to the parameters below, resetting hurts a bit but leaving
+	 * it might result in an unreasonable qavg for a while. --TGR
+	 */
+	v->qavg		= 0;
+
+	v->qcount	= -1;
+}
+
+static inline bool red_check_params(u32 qth_min, u32 qth_max, u8 Wlog,
+				    u8 Scell_log, u8 *stab)
+{
+	if (fls(qth_min) + Wlog >= 32)
+		return false;
+	if (fls(qth_max) + Wlog >= 32)
+		return false;
+	if (Scell_log >= 32)
+		return false;
+	if (qth_max < qth_min)
+		return false;
+	if (stab) {
+		int i;
+
+		for (i = 0; i < RED_STAB_SIZE; i++)
+			if (stab[i] >= 32)
+				return false;
+	}
+	return true;
+}
+
+static inline int red_get_flags(unsigned char qopt_flags,
+				unsigned char historic_mask,
+				struct nlattr *flags_attr,
+				unsigned char supported_mask,
+				struct nla_bitfield32 *p_flags,
+				unsigned char *p_userbits,
+				struct netlink_ext_ack *extack)
+{
+	struct nla_bitfield32 flags;
+
+	if (qopt_flags && flags_attr) {
+		NL_SET_ERR_MSG_MOD(extack, "flags should be passed either through qopt, or through a dedicated attribute");
+		return -EINVAL;
+	}
+
+	if (flags_attr) {
+		flags = nla_get_bitfield32(flags_attr);
+	} else {
+		flags.selector = historic_mask;
+		flags.value = qopt_flags & historic_mask;
+	}
+
+	*p_flags = flags;
+	*p_userbits = qopt_flags & ~historic_mask;
+	return 0;
+}
+
+static inline int red_validate_flags(unsigned char flags,
+				     struct netlink_ext_ack *extack)
+{
+	if ((flags & TC_RED_NODROP) && !(flags & TC_RED_ECN)) {
+		NL_SET_ERR_MSG_MOD(extack, "nodrop mode is only meaningful with ECN");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static inline void red_set_parms(struct red_parms *p,
+				 u32 qth_min, u32 qth_max, u8 Wlog, u8 Plog,
+				 u8 Scell_log, u8 *stab, u32 max_P)
+{
+	int delta = qth_max - qth_min;
+	u32 max_p_delta;
+
+	WRITE_ONCE(p->qth_min, qth_min << Wlog);
+	WRITE_ONCE(p->qth_max, qth_max << Wlog);
+	WRITE_ONCE(p->Wlog, Wlog);
+	WRITE_ONCE(p->Plog, Plog);
+	if (delta <= 0)
+		delta = 1;
+	p->qth_delta	= delta;
+	if (!max_P) {
+		max_P = red_maxp(Plog);
+		max_P *= delta; /* max_P = (qth_max - qth_min)/2^Plog */
+	}
+	WRITE_ONCE(p->max_P, max_P);
+	max_p_delta = max_P / delta;
+	max_p_delta = max(max_p_delta, 1U);
+	p->max_P_reciprocal  = reciprocal_value(max_p_delta);
+
+	/* RED Adaptative target :
+	 * [min_th + 0.4*(min_th - max_th),
+	 *  min_th + 0.6*(min_th - max_th)].
+	 */
+	delta /= 5;
+	p->target_min = qth_min + 2*delta;
+	p->target_max = qth_min + 3*delta;
+
+	WRITE_ONCE(p->Scell_log, Scell_log);
+	p->Scell_max	= (255 << Scell_log);
+
+	if (stab)
+		memcpy(p->Stab, stab, sizeof(p->Stab));
+}
+
+static inline int red_is_idling(const struct red_vars *v)
+{
+	return v->qidlestart != 0;
+}
+
+static inline void red_start_of_idle_period(struct red_vars *v)
+{
+	v->qidlestart = ktime_get();
+}
+
+static inline void red_end_of_idle_period(struct red_vars *v)
+{
+	v->qidlestart = 0;
+}
+
+static inline void red_restart(struct red_vars *v)
+{
+	red_end_of_idle_period(v);
+	v->qavg = 0;
+	v->qcount = -1;
+}
+
+static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms *p,
+							 const struct red_vars *v)
+{
+	s64 delta = ktime_us_delta(ktime_get(), v->qidlestart);
+	long us_idle = min_t(s64, delta, p->Scell_max);
+	int  shift;
+
+	/*
+	 * The problem: ideally, average length queue recalculation should
+	 * be done over constant clock intervals. This is too expensive, so
+	 * that the calculation is driven by outgoing packets.
+	 * When the queue is idle we have to model this clock by hand.
+	 *
+	 * SF+VJ proposed to "generate":
+	 *
+	 *	m = idletime / (average_pkt_size / bandwidth)
+	 *
+	 * dummy packets as a burst after idle time, i.e.
+	 *
+	 * 	v->qavg *= (1-W)^m
+	 *
+	 * This is an apparently overcomplicated solution (f.e. we have to
+	 * precompute a table to make this calculation in reasonable time)
+	 * I believe that a simpler model may be used here,
+	 * but it is field for experiments.
+	 */
+
+	shift = p->Stab[(us_idle >> p->Scell_log) & RED_STAB_MASK];
+
+	if (shift)
+		return v->qavg >> shift;
+	else {
+		/* Approximate initial part of exponent with linear function:
+		 *
+		 * 	(1-W)^m ~= 1-mW + ...
+		 *
+		 * Seems, it is the best solution to
+		 * problem of too coarse exponent tabulation.
+		 */
+		us_idle = (v->qavg * (u64)us_idle) >> p->Scell_log;
+
+		if (us_idle < (v->qavg >> 1))
+			return v->qavg - us_idle;
+		else
+			return v->qavg >> 1;
+	}
+}
+
+static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p,
+						       const struct red_vars *v,
+						       unsigned int backlog)
+{
+	/*
+	 * NOTE: v->qavg is fixed point number with point at Wlog.
+	 * The formula below is equivalent to floating point
+	 * version:
+	 *
+	 * 	qavg = qavg*(1-W) + backlog*W;
+	 *
+	 * --ANK (980924)
+	 */
+	return v->qavg + (backlog - (v->qavg >> p->Wlog));
+}
+
+static inline unsigned long red_calc_qavg(const struct red_parms *p,
+					  const struct red_vars *v,
+					  unsigned int backlog)
+{
+	if (!red_is_idling(v))
+		return red_calc_qavg_no_idle_time(p, v, backlog);
+	else
+		return red_calc_qavg_from_idle_time(p, v);
+}
+
+
+static inline u32 red_random(const struct red_parms *p)
+{
+	return reciprocal_divide(get_random_u32(), p->max_P_reciprocal);
+}
+
+static inline int red_mark_probability(const struct red_parms *p,
+				       const struct red_vars *v,
+				       unsigned long qavg)
+{
+	/* The formula used below causes questions.
+
+	   OK. qR is random number in the interval
+		(0..1/max_P)*(qth_max-qth_min)
+	   i.e. 0..(2^Plog). If we used floating point
+	   arithmetic, it would be: (2^Plog)*rnd_num,
+	   where rnd_num is less 1.
+
+	   Taking into account, that qavg have fixed
+	   point at Wlog, two lines
+	   below have the following floating point equivalent:
+
+	   max_P*(qavg - qth_min)/(qth_max-qth_min) < rnd/qcount
+
+	   Any questions? --ANK (980924)
+	 */
+	return !(((qavg - p->qth_min) >> p->Wlog) * v->qcount < v->qR);
+}
+
+enum {
+	RED_BELOW_MIN_THRESH,
+	RED_BETWEEN_TRESH,
+	RED_ABOVE_MAX_TRESH,
+};
+
+static inline int red_cmp_thresh(const struct red_parms *p, unsigned long qavg)
+{
+	if (qavg < p->qth_min)
+		return RED_BELOW_MIN_THRESH;
+	else if (qavg >= p->qth_max)
+		return RED_ABOVE_MAX_TRESH;
+	else
+		return RED_BETWEEN_TRESH;
+}
+
+enum {
+	RED_DONT_MARK,
+	RED_PROB_MARK,
+	RED_HARD_MARK,
+};
+
+static inline int red_action(const struct red_parms *p,
+			     struct red_vars *v,
+			     unsigned long qavg)
+{
+	switch (red_cmp_thresh(p, qavg)) {
+		case RED_BELOW_MIN_THRESH:
+			v->qcount = -1;
+			return RED_DONT_MARK;
+
+		case RED_BETWEEN_TRESH:
+			if (++v->qcount) {
+				if (red_mark_probability(p, v, qavg)) {
+					v->qcount = 0;
+					v->qR = red_random(p);
+					return RED_PROB_MARK;
+				}
+			} else
+				v->qR = red_random(p);
+
+			return RED_DONT_MARK;
+
+		case RED_ABOVE_MAX_TRESH:
+			v->qcount = -1;
+			return RED_HARD_MARK;
+	}
+
+	BUG();
+	return RED_DONT_MARK;
+}
+
+static inline void red_adaptative_algo(struct red_parms *p, struct red_vars *v)
+{
+	unsigned long qavg;
+	u32 max_p_delta;
+
+	qavg = v->qavg;
+	if (red_is_idling(v))
+		qavg = red_calc_qavg_from_idle_time(p, v);
+
+	/* v->qavg is fixed point number with point at Wlog */
+	qavg >>= p->Wlog;
+
+	if (qavg > p->target_max && p->max_P <= MAX_P_MAX)
+		p->max_P += MAX_P_ALPHA(p->max_P); /* maxp = maxp + alpha */
+	else if (qavg < p->target_min && p->max_P >= MAX_P_MIN)
+		p->max_P = (p->max_P/10)*9; /* maxp = maxp * Beta */
+
+	max_p_delta = DIV_ROUND_CLOSEST(p->max_P, p->qth_delta);
+	max_p_delta = max(max_p_delta, 1U);
+	p->max_P_reciprocal = reciprocal_value(max_p_delta);
+}
+#endif