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, 637 insertions, 0 deletions

diff --git a/drivers/usb/host/uhci-debug.c b/drivers/usb/host/uhci-debug.c
new file mode 100644
index 000000000..e91ec6a4f
--- /dev/null
+++ b/drivers/usb/host/uhci-debug.c
@@ -0,0 +1,637 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UHCI-specific debugging code. Invaluable when something
+ * goes wrong, but don't get in my face.
+ *
+ * Kernel visible pointers are surrounded in []s and bus
+ * visible pointers are surrounded in ()s
+ *
+ * (C) Copyright 1999 Linus Torvalds
+ * (C) Copyright 1999-2001 Johannes Erdfelt
+ */
+
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/debugfs.h>
+#include <asm/io.h>
+
+#include "uhci-hcd.h"
+
+#define EXTRA_SPACE	1024
+
+static struct dentry *uhci_debugfs_root;
+
+#ifdef CONFIG_DYNAMIC_DEBUG
+
+/* Handle REALLY large printks so we don't overflow buffers */
+static void lprintk(char *buf)
+{
+	char *p;
+
+	/* Just write one line at a time */
+	while (buf) {
+		p = strchr(buf, '\n');
+		if (p)
+			*p = 0;
+		printk(KERN_DEBUG "%s\n", buf);
+		buf = p;
+		if (buf)
+			buf++;
+	}
+}
+
+static int uhci_show_td(struct uhci_hcd *uhci, struct uhci_td *td, char *buf,
+			int len, int space)
+{
+	char *out = buf;
+	char *spid;
+	u32 status, token;
+
+	status = td_status(uhci, td);
+	out += sprintf(out, "%*s[%p] link (%08x) ", space, "", td,
+		hc32_to_cpu(uhci, td->link));
+	out += sprintf(out, "e%d %s%s%s%s%s%s%s%s%s%sLength=%x ",
+		((status >> 27) & 3),
+		(status & TD_CTRL_SPD) ?      "SPD " : "",
+		(status & TD_CTRL_LS) ?       "LS " : "",
+		(status & TD_CTRL_IOC) ?      "IOC " : "",
+		(status & TD_CTRL_ACTIVE) ?   "Active " : "",
+		(status & TD_CTRL_STALLED) ?  "Stalled " : "",
+		(status & TD_CTRL_DBUFERR) ?  "DataBufErr " : "",
+		(status & TD_CTRL_BABBLE) ?   "Babble " : "",
+		(status & TD_CTRL_NAK) ?      "NAK " : "",
+		(status & TD_CTRL_CRCTIMEO) ? "CRC/Timeo " : "",
+		(status & TD_CTRL_BITSTUFF) ? "BitStuff " : "",
+		status & 0x7ff);
+	if (out - buf > len)
+		goto done;
+
+	token = td_token(uhci, td);
+	switch (uhci_packetid(token)) {
+		case USB_PID_SETUP:
+			spid = "SETUP";
+			break;
+		case USB_PID_OUT:
+			spid = "OUT";
+			break;
+		case USB_PID_IN:
+			spid = "IN";
+			break;
+		default:
+			spid = "?";
+			break;
+	}
+
+	out += sprintf(out, "MaxLen=%x DT%d EndPt=%x Dev=%x, PID=%x(%s) ",
+		token >> 21,
+		((token >> 19) & 1),
+		(token >> 15) & 15,
+		(token >> 8) & 127,
+		(token & 0xff),
+		spid);
+	out += sprintf(out, "(buf=%08x)\n", hc32_to_cpu(uhci, td->buffer));
+
+done:
+	if (out - buf > len)
+		out += sprintf(out, " ...\n");
+	return out - buf;
+}
+
+static int uhci_show_urbp(struct uhci_hcd *uhci, struct urb_priv *urbp,
+			char *buf, int len, int space)
+{
+	char *out = buf;
+	struct uhci_td *td;
+	int i, nactive, ninactive;
+	char *ptype;
+
+
+	out += sprintf(out, "urb_priv [%p] ", urbp);
+	out += sprintf(out, "urb [%p] ", urbp->urb);
+	out += sprintf(out, "qh [%p] ", urbp->qh);
+	out += sprintf(out, "Dev=%d ", usb_pipedevice(urbp->urb->pipe));
+	out += sprintf(out, "EP=%x(%s) ", usb_pipeendpoint(urbp->urb->pipe),
+			(usb_pipein(urbp->urb->pipe) ? "IN" : "OUT"));
+	if (out - buf > len)
+		goto done;
+
+	switch (usb_pipetype(urbp->urb->pipe)) {
+	case PIPE_ISOCHRONOUS: ptype = "ISO"; break;
+	case PIPE_INTERRUPT: ptype = "INT"; break;
+	case PIPE_BULK: ptype = "BLK"; break;
+	default:
+	case PIPE_CONTROL: ptype = "CTL"; break;
+	}
+
+	out += sprintf(out, "%s%s", ptype, (urbp->fsbr ? " FSBR" : ""));
+	out += sprintf(out, " Actlen=%d%s", urbp->urb->actual_length,
+			(urbp->qh->type == USB_ENDPOINT_XFER_CONTROL ?
+				"-8" : ""));
+
+	if (urbp->urb->unlinked)
+		out += sprintf(out, " Unlinked=%d", urbp->urb->unlinked);
+	out += sprintf(out, "\n");
+
+	if (out - buf > len)
+		goto done;
+
+	i = nactive = ninactive = 0;
+	list_for_each_entry(td, &urbp->td_list, list) {
+		if (urbp->qh->type != USB_ENDPOINT_XFER_ISOC &&
+				(++i <= 10 || debug > 2)) {
+			out += sprintf(out, "%*s%d: ", space + 2, "", i);
+			out += uhci_show_td(uhci, td, out,
+					len - (out - buf), 0);
+			if (out - buf > len)
+				goto tail;
+		} else {
+			if (td_status(uhci, td) & TD_CTRL_ACTIVE)
+				++nactive;
+			else
+				++ninactive;
+		}
+	}
+	if (nactive + ninactive > 0)
+		out += sprintf(out,
+				"%*s[skipped %d inactive and %d active TDs]\n",
+				space, "", ninactive, nactive);
+done:
+	if (out - buf > len)
+		out += sprintf(out, " ...\n");
+tail:
+	return out - buf;
+}
+
+static int uhci_show_qh(struct uhci_hcd *uhci,
+		struct uhci_qh *qh, char *buf, int len, int space)
+{
+	char *out = buf;
+	int i, nurbs;
+	__hc32 element = qh_element(qh);
+	char *qtype;
+
+	switch (qh->type) {
+	case USB_ENDPOINT_XFER_ISOC: qtype = "ISO"; break;
+	case USB_ENDPOINT_XFER_INT: qtype = "INT"; break;
+	case USB_ENDPOINT_XFER_BULK: qtype = "BLK"; break;
+	case USB_ENDPOINT_XFER_CONTROL: qtype = "CTL"; break;
+	default: qtype = "Skel" ; break;
+	}
+
+	out += sprintf(out, "%*s[%p] %s QH link (%08x) element (%08x)\n",
+			space, "", qh, qtype,
+			hc32_to_cpu(uhci, qh->link),
+			hc32_to_cpu(uhci, element));
+	if (qh->type == USB_ENDPOINT_XFER_ISOC)
+		out += sprintf(out,
+				"%*s    period %d phase %d load %d us, frame %x desc [%p]\n",
+				space, "", qh->period, qh->phase, qh->load,
+				qh->iso_frame, qh->iso_packet_desc);
+	else if (qh->type == USB_ENDPOINT_XFER_INT)
+		out += sprintf(out, "%*s    period %d phase %d load %d us\n",
+				space, "", qh->period, qh->phase, qh->load);
+	if (out - buf > len)
+		goto done;
+
+	if (element & UHCI_PTR_QH(uhci))
+		out += sprintf(out, "%*s  Element points to QH (bug?)\n", space, "");
+
+	if (element & UHCI_PTR_DEPTH(uhci))
+		out += sprintf(out, "%*s  Depth traverse\n", space, "");
+
+	if (element & cpu_to_hc32(uhci, 8))
+		out += sprintf(out, "%*s  Bit 3 set (bug?)\n", space, "");
+
+	if (!(element & ~(UHCI_PTR_QH(uhci) | UHCI_PTR_DEPTH(uhci))))
+		out += sprintf(out, "%*s  Element is NULL (bug?)\n", space, "");
+
+	if (out - buf > len)
+		goto done;
+
+	if (list_empty(&qh->queue)) {
+		out += sprintf(out, "%*s  queue is empty\n", space, "");
+		if (qh == uhci->skel_async_qh) {
+			out += uhci_show_td(uhci, uhci->term_td, out,
+					len - (out - buf), 0);
+			if (out - buf > len)
+				goto tail;
+		}
+	} else {
+		struct urb_priv *urbp = list_entry(qh->queue.next,
+				struct urb_priv, node);
+		struct uhci_td *td = list_entry(urbp->td_list.next,
+				struct uhci_td, list);
+
+		if (element != LINK_TO_TD(uhci, td))
+			out += sprintf(out, "%*s Element != First TD\n",
+					space, "");
+		i = nurbs = 0;
+		list_for_each_entry(urbp, &qh->queue, node) {
+			if (++i <= 10) {
+				out += uhci_show_urbp(uhci, urbp, out,
+						len - (out - buf), space + 2);
+				if (out - buf > len)
+					goto tail;
+			}
+			else
+				++nurbs;
+		}
+		if (nurbs > 0)
+			out += sprintf(out, "%*s Skipped %d URBs\n",
+					space, "", nurbs);
+	}
+
+	if (out - buf > len)
+		goto done;
+
+	if (qh->dummy_td) {
+		out += sprintf(out, "%*s  Dummy TD\n", space, "");
+		out += uhci_show_td(uhci, qh->dummy_td, out,
+				len - (out - buf), 0);
+		if (out - buf > len)
+			goto tail;
+	}
+
+done:
+	if (out - buf > len)
+		out += sprintf(out, " ...\n");
+tail:
+	return out - buf;
+}
+
+static int uhci_show_sc(int port, unsigned short status, char *buf)
+{
+	return sprintf(buf, "  stat%d     =     %04x  %s%s%s%s%s%s%s%s%s%s\n",
+		port,
+		status,
+		(status & USBPORTSC_SUSP) ?	" Suspend" : "",
+		(status & USBPORTSC_OCC) ?	" OverCurrentChange" : "",
+		(status & USBPORTSC_OC) ?	" OverCurrent" : "",
+		(status & USBPORTSC_PR) ?	" Reset" : "",
+		(status & USBPORTSC_LSDA) ?	" LowSpeed" : "",
+		(status & USBPORTSC_RD) ?	" ResumeDetect" : "",
+		(status & USBPORTSC_PEC) ?	" EnableChange" : "",
+		(status & USBPORTSC_PE) ?	" Enabled" : "",
+		(status & USBPORTSC_CSC) ?	" ConnectChange" : "",
+		(status & USBPORTSC_CCS) ?	" Connected" : "");
+}
+
+static int uhci_show_root_hub_state(struct uhci_hcd *uhci, char *buf)
+{
+	char *rh_state;
+
+	switch (uhci->rh_state) {
+	    case UHCI_RH_RESET:
+		rh_state = "reset";		break;
+	    case UHCI_RH_SUSPENDED:
+		rh_state = "suspended";		break;
+	    case UHCI_RH_AUTO_STOPPED:
+		rh_state = "auto-stopped";	break;
+	    case UHCI_RH_RESUMING:
+		rh_state = "resuming";		break;
+	    case UHCI_RH_SUSPENDING:
+		rh_state = "suspending";	break;
+	    case UHCI_RH_RUNNING:
+		rh_state = "running";		break;
+	    case UHCI_RH_RUNNING_NODEVS:
+		rh_state = "running, no devs";	break;
+	    default:
+		rh_state = "?";			break;
+	}
+	return sprintf(buf, "Root-hub state: %s   FSBR: %d\n",
+			rh_state, uhci->fsbr_is_on);
+}
+
+static int uhci_show_status(struct uhci_hcd *uhci, char *buf, int len)
+{
+	char *out = buf;
+	unsigned short usbcmd, usbstat, usbint, usbfrnum;
+	unsigned int flbaseadd;
+	unsigned char sof;
+	unsigned short portsc1, portsc2;
+
+
+	usbcmd    = uhci_readw(uhci, USBCMD);
+	usbstat   = uhci_readw(uhci, USBSTS);
+	usbint    = uhci_readw(uhci, USBINTR);
+	usbfrnum  = uhci_readw(uhci, USBFRNUM);
+	flbaseadd = uhci_readl(uhci, USBFLBASEADD);
+	sof       = uhci_readb(uhci, USBSOF);
+	portsc1   = uhci_readw(uhci, USBPORTSC1);
+	portsc2   = uhci_readw(uhci, USBPORTSC2);
+
+	out += sprintf(out, "  usbcmd    =     %04x   %s%s%s%s%s%s%s%s\n",
+		usbcmd,
+		(usbcmd & USBCMD_MAXP) ?    "Maxp64 " : "Maxp32 ",
+		(usbcmd & USBCMD_CF) ?      "CF " : "",
+		(usbcmd & USBCMD_SWDBG) ?   "SWDBG " : "",
+		(usbcmd & USBCMD_FGR) ?     "FGR " : "",
+		(usbcmd & USBCMD_EGSM) ?    "EGSM " : "",
+		(usbcmd & USBCMD_GRESET) ?  "GRESET " : "",
+		(usbcmd & USBCMD_HCRESET) ? "HCRESET " : "",
+		(usbcmd & USBCMD_RS) ?      "RS " : "");
+	if (out - buf > len)
+		goto done;
+
+	out += sprintf(out, "  usbstat   =     %04x   %s%s%s%s%s%s\n",
+		usbstat,
+		(usbstat & USBSTS_HCH) ?    "HCHalted " : "",
+		(usbstat & USBSTS_HCPE) ?   "HostControllerProcessError " : "",
+		(usbstat & USBSTS_HSE) ?    "HostSystemError " : "",
+		(usbstat & USBSTS_RD) ?     "ResumeDetect " : "",
+		(usbstat & USBSTS_ERROR) ?  "USBError " : "",
+		(usbstat & USBSTS_USBINT) ? "USBINT " : "");
+	if (out - buf > len)
+		goto done;
+
+	out += sprintf(out, "  usbint    =     %04x\n", usbint);
+	out += sprintf(out, "  usbfrnum  =   (%d)%03x\n", (usbfrnum >> 10) & 1,
+		0xfff & (4*(unsigned int)usbfrnum));
+	out += sprintf(out, "  flbaseadd = %08x\n", flbaseadd);
+	out += sprintf(out, "  sof       =       %02x\n", sof);
+	if (out - buf > len)
+		goto done;
+
+	out += uhci_show_sc(1, portsc1, out);
+	if (out - buf > len)
+		goto done;
+
+	out += uhci_show_sc(2, portsc2, out);
+	if (out - buf > len)
+		goto done;
+
+	out += sprintf(out,
+			"Most recent frame: %x (%d)   Last ISO frame: %x (%d)\n",
+			uhci->frame_number, uhci->frame_number & 1023,
+			uhci->last_iso_frame, uhci->last_iso_frame & 1023);
+
+done:
+	if (out - buf > len)
+		out += sprintf(out, " ...\n");
+	return out - buf;
+}
+
+static int uhci_sprint_schedule(struct uhci_hcd *uhci, char *buf, int len)
+{
+	char *out = buf;
+	int i, j;
+	struct uhci_qh *qh;
+	struct uhci_td *td;
+	struct list_head *tmp, *head;
+	int nframes, nerrs;
+	__hc32 link;
+	__hc32 fsbr_link;
+
+	static const char * const qh_names[] = {
+		"unlink", "iso", "int128", "int64", "int32", "int16",
+		"int8", "int4", "int2", "async", "term"
+	};
+
+	out += uhci_show_root_hub_state(uhci, out);
+	if (out - buf > len)
+		goto done;
+	out += sprintf(out, "HC status\n");
+	out += uhci_show_status(uhci, out, len - (out - buf));
+	if (out - buf > len)
+		goto tail;
+
+	out += sprintf(out, "Periodic load table\n");
+	for (i = 0; i < MAX_PHASE; ++i) {
+		out += sprintf(out, "\t%d", uhci->load[i]);
+		if (i % 8 == 7)
+			*out++ = '\n';
+	}
+	out += sprintf(out, "Total: %d, #INT: %d, #ISO: %d\n",
+			uhci->total_load,
+			uhci_to_hcd(uhci)->self.bandwidth_int_reqs,
+			uhci_to_hcd(uhci)->self.bandwidth_isoc_reqs);
+	if (debug <= 1)
+		goto tail;
+
+	out += sprintf(out, "Frame List\n");
+	nframes = 10;
+	nerrs = 0;
+	for (i = 0; i < UHCI_NUMFRAMES; ++i) {
+		__hc32 qh_dma;
+
+		if (out - buf > len)
+			goto done;
+		j = 0;
+		td = uhci->frame_cpu[i];
+		link = uhci->frame[i];
+		if (!td)
+			goto check_link;
+
+		if (nframes > 0) {
+			out += sprintf(out, "- Frame %d -> (%08x)\n",
+					i, hc32_to_cpu(uhci, link));
+			j = 1;
+		}
+
+		head = &td->fl_list;
+		tmp = head;
+		do {
+			td = list_entry(tmp, struct uhci_td, fl_list);
+			tmp = tmp->next;
+			if (link != LINK_TO_TD(uhci, td)) {
+				if (nframes > 0) {
+					out += sprintf(out,
+						"    link does not match list entry!\n");
+					if (out - buf > len)
+						goto done;
+				} else
+					++nerrs;
+			}
+			if (nframes > 0) {
+				out += uhci_show_td(uhci, td, out,
+						len - (out - buf), 4);
+				if (out - buf > len)
+					goto tail;
+			}
+			link = td->link;
+		} while (tmp != head);
+
+check_link:
+		qh_dma = uhci_frame_skel_link(uhci, i);
+		if (link != qh_dma) {
+			if (nframes > 0) {
+				if (!j) {
+					out += sprintf(out,
+						"- Frame %d -> (%08x)\n",
+						i, hc32_to_cpu(uhci, link));
+					j = 1;
+				}
+				out += sprintf(out,
+					"   link does not match QH (%08x)!\n",
+					hc32_to_cpu(uhci, qh_dma));
+				if (out - buf > len)
+					goto done;
+			} else
+				++nerrs;
+		}
+		nframes -= j;
+	}
+	if (nerrs > 0)
+		out += sprintf(out, "Skipped %d bad links\n", nerrs);
+
+	out += sprintf(out, "Skeleton QHs\n");
+
+	if (out - buf > len)
+		goto done;
+
+	fsbr_link = 0;
+	for (i = 0; i < UHCI_NUM_SKELQH; ++i) {
+		int cnt = 0;
+
+		qh = uhci->skelqh[i];
+		out += sprintf(out, "- skel_%s_qh\n", qh_names[i]);
+		out += uhci_show_qh(uhci, qh, out, len - (out - buf), 4);
+		if (out - buf > len)
+			goto tail;
+
+		/* Last QH is the Terminating QH, it's different */
+		if (i == SKEL_TERM) {
+			if (qh_element(qh) != LINK_TO_TD(uhci, uhci->term_td)) {
+				out += sprintf(out,
+					"    skel_term_qh element is not set to term_td!\n");
+				if (out - buf > len)
+					goto done;
+			}
+			link = fsbr_link;
+			if (!link)
+				link = LINK_TO_QH(uhci, uhci->skel_term_qh);
+			goto check_qh_link;
+		}
+
+		head = &qh->node;
+		tmp = head->next;
+
+		while (tmp != head) {
+			qh = list_entry(tmp, struct uhci_qh, node);
+			tmp = tmp->next;
+			if (++cnt <= 10) {
+				out += uhci_show_qh(uhci, qh, out,
+						len - (out - buf), 4);
+				if (out - buf > len)
+					goto tail;
+			}
+			if (!fsbr_link && qh->skel >= SKEL_FSBR)
+				fsbr_link = LINK_TO_QH(uhci, qh);
+		}
+		if ((cnt -= 10) > 0)
+			out += sprintf(out, "    Skipped %d QHs\n", cnt);
+
+		link = UHCI_PTR_TERM(uhci);
+		if (i <= SKEL_ISO)
+			;
+		else if (i < SKEL_ASYNC)
+			link = LINK_TO_QH(uhci, uhci->skel_async_qh);
+		else if (!uhci->fsbr_is_on)
+			;
+		else
+			link = LINK_TO_QH(uhci, uhci->skel_term_qh);
+check_qh_link:
+		if (qh->link != link)
+			out += sprintf(out,
+				"    last QH not linked to next skeleton!\n");
+
+		if (out - buf > len)
+			goto done;
+	}
+
+done:
+	if (out - buf > len)
+		out += sprintf(out, " ...\n");
+tail:
+	return out - buf;
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+#define MAX_OUTPUT	(64 * 1024)
+
+struct uhci_debug {
+	int size;
+	char *data;
+};
+
+static int uhci_debug_open(struct inode *inode, struct file *file)
+{
+	struct uhci_hcd *uhci = inode->i_private;
+	struct uhci_debug *up;
+	unsigned long flags;
+
+	up = kmalloc_obj(*up);
+	if (!up)
+		return -ENOMEM;
+
+	up->data = kmalloc(MAX_OUTPUT, GFP_KERNEL);
+	if (!up->data) {
+		kfree(up);
+		return -ENOMEM;
+	}
+
+	up->size = 0;
+	spin_lock_irqsave(&uhci->lock, flags);
+	if (uhci->is_initialized)
+		up->size = uhci_sprint_schedule(uhci, up->data,
+					MAX_OUTPUT - EXTRA_SPACE);
+	spin_unlock_irqrestore(&uhci->lock, flags);
+
+	file->private_data = up;
+
+	return 0;
+}
+
+static loff_t uhci_debug_lseek(struct file *file, loff_t off, int whence)
+{
+	struct uhci_debug *up = file->private_data;
+	return no_seek_end_llseek_size(file, off, whence, up->size);
+}
+
+static ssize_t uhci_debug_read(struct file *file, char __user *buf,
+				size_t nbytes, loff_t *ppos)
+{
+	struct uhci_debug *up = file->private_data;
+	return simple_read_from_buffer(buf, nbytes, ppos, up->data, up->size);
+}
+
+static int uhci_debug_release(struct inode *inode, struct file *file)
+{
+	struct uhci_debug *up = file->private_data;
+
+	kfree(up->data);
+	kfree(up);
+
+	return 0;
+}
+
+static const struct file_operations uhci_debug_operations = {
+	.owner =	THIS_MODULE,
+	.open =		uhci_debug_open,
+	.llseek =	uhci_debug_lseek,
+	.read =		uhci_debug_read,
+	.release =	uhci_debug_release,
+};
+#define UHCI_DEBUG_OPS
+
+#endif	/* CONFIG_DEBUG_FS */
+
+#else	/* CONFIG_DYNAMIC_DEBUG*/
+
+static inline void lprintk(char *buf)
+{}
+
+static inline int uhci_show_qh(struct uhci_hcd *uhci,
+		struct uhci_qh *qh, char *buf, int len, int space)
+{
+	return 0;
+}
+
+static inline int uhci_sprint_schedule(struct uhci_hcd *uhci,
+		char *buf, int len)
+{
+	return 0;
+}
+
+#endif