[PATCH] UHCI: improve debugging code

This patch (as626) makes some improvements to the debugging code in
uhci-hcd.  The main change is that now the code won't get compiled if
CONFIG_USB_DEBUG isn't set.  But there are other changes too, like
adding a missing .owner field and printing a debugging dump if the
controller dies.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 70 insertions, 39 deletions

diff --git a/drivers/usb/host/uhci-debug.c b/drivers/usb/host/uhci-debug.c
index f2f5f8ce1715..e1239319655c 100644
--- a/drivers/usb/host/uhci-debug.c
+++ b/drivers/usb/host/uhci-debug.c
@@ -17,10 +17,13 @@
 
 #include "uhci-hcd.h"
 
-static struct dentry *uhci_debugfs_root = NULL;
+#define uhci_debug_operations (* (struct file_operations *) NULL)
+static struct dentry *uhci_debugfs_root;
+
+#ifdef DEBUG
 
 /* Handle REALLY large printks so we don't overflow buffers */
-static inline void lprintk(char *buf)
+static void lprintk(char *buf)
 {
         char *p;
 
@@ -196,7 +199,6 @@ static int uhci_show_qh(struct uhci_qh *qh, char *buf, int len, int space)
         return out - buf;
 }
 
-#ifdef CONFIG_PROC_FS
 static const char * const qh_names[] = {
   "skel_unlink_qh", "skel_iso_qh",
   "skel_int128_qh", "skel_int64_qh",
@@ -393,12 +395,13 @@ static int uhci_sprint_schedule(struct uhci_hcd *uhci, char *buf, int len)
         return out - buf;
 }
 
+#ifdef CONFIG_DEBUG_FS
+
 #define MAX_OUTPUT      (64 * 1024)
 
 struct uhci_debug {
         int size;
         char *data;
-        struct uhci_hcd *uhci;
 };
 
 static int uhci_debug_open(struct inode *inode, struct file *file)
@@ -419,8 +422,10 @@ static int uhci_debug_open(struct inode *inode, struct file *file)
                 goto out;
         }
 
+        up->size = 0;
         spin_lock_irqsave(&uhci->lock, flags);
-        up->size = uhci_sprint_schedule(uhci, up->data, MAX_OUTPUT);
+        if (uhci->is_initialized)
+                up->size = uhci_sprint_schedule(uhci, up->data, MAX_OUTPUT);
         spin_unlock_irqrestore(&uhci->lock, flags);
 
         file->private_data = up;
@@ -472,15 +477,32 @@ static int uhci_debug_release(struct inode *inode, struct file *file)
         return 0;
 }
 
+#undef uhci_debug_operations
 static 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,
 };
 
-#else   /* CONFIG_DEBUG_FS */
+#endif  /* CONFIG_DEBUG_FS */
 
-#define uhci_debug_operations (* (struct file_operations *) NULL)
+#else   /* DEBUG */
+
+static inline void lprintk(char *buf)
+{}
+
+static inline int uhci_show_qh(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
diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index 9865f303d3fc..4edb8330c440 100644
--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -68,12 +68,16 @@ Alan Stern"
  * debug = 3, show all TDs in URBs when dumping
  */
 #ifdef DEBUG
+#define DEBUG_CONFIGURED        1
 static int debug = 1;
-#else
-static int debug = 0;
-#endif
 module_param(debug, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(debug, "Debug level");
+
+#else
+#define DEBUG_CONFIGURED        0
+#define debug                   0
+#endif
+
 static char *errbuf;
 #define ERRBUF_LEN    (32 * 1024)
 
@@ -338,6 +342,12 @@ static irqreturn_t uhci_irq(struct usb_hcd *hcd, struct pt_regs *regs)
                                 dev_err(uhci_dev(uhci),
                                         "host controller halted, "
                                         "very bad!\n");
+                                if (debug > 1 && errbuf) {
+                                        /* Print the schedule for debugging */
+                                        uhci_sprint_schedule(uhci,
+                                                        errbuf, ERRBUF_LEN);
+                                        lprintk(errbuf);
+                                }
                                 hc_died(uhci);
 
                                 /* Force a callback in case there are
@@ -376,6 +386,14 @@ static void release_uhci(struct uhci_hcd *uhci)
 {
         int i;
 
+        if (DEBUG_CONFIGURED) {
+                spin_lock_irq(&uhci->lock);
+                uhci->is_initialized = 0;
+                spin_unlock_irq(&uhci->lock);
+
+                debugfs_remove(uhci->dentry);
+        }
+
         for (i = 0; i < UHCI_NUM_SKELQH; i++)
                 uhci_free_qh(uhci, uhci->skelqh[i]);
 
@@ -390,8 +408,6 @@ static void release_uhci(struct uhci_hcd *uhci)
         dma_free_coherent(uhci_dev(uhci),
                         UHCI_NUMFRAMES * sizeof(*uhci->frame),
                         uhci->frame, uhci->frame_dma_handle);
-
-        debugfs_remove(uhci->dentry);
 }
 
 static int uhci_reset(struct usb_hcd *hcd)
@@ -474,17 +490,6 @@ static int uhci_start(struct usb_hcd *hcd)
 
         hcd->uses_new_polling = 1;
 
-        dentry = debugfs_create_file(hcd->self.bus_name,
-                        S_IFREG|S_IRUGO|S_IWUSR, uhci_debugfs_root, uhci,
-                        &uhci_debug_operations);
-        if (!dentry) {
-                dev_err(uhci_dev(uhci),
-                                "couldn't create uhci debugfs entry\n");
-                retval = -ENOMEM;
-                goto err_create_debug_entry;
-        }
-        uhci->dentry = dentry;
-
         uhci->fsbr = 0;
         uhci->fsbrtimeout = 0;
 
@@ -495,6 +500,19 @@ static int uhci_start(struct usb_hcd *hcd)
 
         init_waitqueue_head(&uhci->waitqh);
 
+        if (DEBUG_CONFIGURED) {
+                dentry = debugfs_create_file(hcd->self.bus_name,
+                                S_IFREG|S_IRUGO|S_IWUSR, uhci_debugfs_root,
+                                uhci, &uhci_debug_operations);
+                if (!dentry) {
+                        dev_err(uhci_dev(uhci), "couldn't create uhci "
+                                        "debugfs entry\n");
+                        retval = -ENOMEM;
+                        goto err_create_debug_entry;
+                }
+                uhci->dentry = dentry;
+        }
+
         uhci->frame = dma_alloc_coherent(uhci_dev(uhci),
                         UHCI_NUMFRAMES * sizeof(*uhci->frame),
                         &uhci->frame_dma_handle, 0);
@@ -609,6 +627,7 @@ static int uhci_start(struct usb_hcd *hcd)
         mb();
 
         configure_hc(uhci);
+        uhci->is_initialized = 1;
         start_rh(uhci);
         return 0;
 
@@ -872,16 +891,15 @@ static int __init uhci_hcd_init(void)
         if (usb_disabled())
                 return -ENODEV;
 
-        if (debug) {
+        if (DEBUG_CONFIGURED) {
                 errbuf = kmalloc(ERRBUF_LEN, GFP_KERNEL);
                 if (!errbuf)
                         goto errbuf_failed;
+                uhci_debugfs_root = debugfs_create_dir("uhci", NULL);
+                if (!uhci_debugfs_root)
+                        goto debug_failed;
         }
 
-        uhci_debugfs_root = debugfs_create_dir("uhci", NULL);
-        if (!uhci_debugfs_root)
-                goto debug_failed;
-
         uhci_up_cachep = kmem_cache_create("uhci_urb_priv",
                 sizeof(struct urb_priv), 0, 0, NULL, NULL);
         if (!uhci_up_cachep)
diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
index 7e96bef2e88f..4a69c7eb09bd 100644
--- a/drivers/usb/host/uhci-hcd.h
+++ b/drivers/usb/host/uhci-hcd.h
@@ -411,6 +411,7 @@ struct uhci_hcd {
         unsigned int hc_inaccessible:1;         /* HC is suspended or dead */
         unsigned int working_RD:1;              /* Suspended root hub doesn't
                                                    need to be polled */
+        unsigned int is_initialized:1;          /* Data structure is usable */
 
         /* Support for port suspend/resume/reset */
         unsigned long port_c_suspend;           /* Bit-arrays of ports */
diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index 44bba9a6d196..5d6c4f75d0d8 100644
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -736,7 +736,6 @@ err:
                 if (errbuf) {
                         /* Print the chain for debugging purposes */
                         uhci_show_qh(urbp->qh, errbuf, ERRBUF_LEN, 0);
-
                         lprintk(errbuf);
                 }
         }
@@ -924,26 +923,17 @@ td_error:
         ret = uhci_map_status(status, uhci_packetout(td_token(td)));
 
 err:
-        /* 
-         * Enable this chunk of code if you want to see some more debugging.
-         * But be careful, it has the tendancy to starve out khubd and prevent
-         * disconnects from happening successfully if you have a slow debug
-         * log interface (like a serial console.
-         */
-#if 0
         if ((debug == 1 && ret != -EPIPE) || debug > 1) {
                 /* Some debugging code */
                 dev_dbg(uhci_dev(uhci), "%s: failed with status %x\n",
                                 __FUNCTION__, status);
 
-                if (errbuf) {
+                if (debug > 1 && errbuf) {
                         /* Print the chain for debugging purposes */
                         uhci_show_qh(urbp->qh, errbuf, ERRBUF_LEN, 0);
-
                         lprintk(errbuf);
                 }
         }
-#endif
 
         /* Note that the queue has stopped and save the next toggle value */
         urbp->qh->element = UHCI_PTR_TERM;