genirq/msi: Capture device name for debugfs

For debugging the allocation of unused or potentially leaked interrupt
descriptor it's helpful to have some information about the site which
allocated them. In case of MSI this is simple because the caller hands the
device struct pointer into the domain allocation function.

Duplicate the device name and show it in the debugfs entry of the interrupt
descriptor.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Yu Chen <yu.c.chen@intel.com>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Len Brown <lenb@kernel.org>
Link: https://lkml.kernel.org/r/20170913213152.433038426@linutronix.de

4 files changed, 21 insertions, 1 deletions

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 3e90a094798d..b55b113c049b 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -93,6 +93,7 @@ struct irq_desc {
 #endif
 #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
         struct dentry           *debugfs_file;
+        const char              *dev_name;
 #endif
 #ifdef CONFIG_SPARSE_IRQ
         struct rcu_head         rcu;
diff --git a/kernel/irq/debugfs.c b/kernel/irq/debugfs.c
index c3fdb36dec30..b7d1023b9b22 100644
--- a/kernel/irq/debugfs.c
+++ b/kernel/irq/debugfs.c
@@ -149,6 +149,7 @@ static int irq_debug_show(struct seq_file *m, void *p)
         raw_spin_lock_irq(&desc->lock);
         data = irq_desc_get_irq_data(desc);
         seq_printf(m, "handler:  %pf\n", desc->handle_irq);
+        seq_printf(m, "device:   %s\n", desc->dev_name);
         seq_printf(m, "status:   0x%08x\n", desc->status_use_accessors);
         irq_debug_show_bits(m, 0, desc->status_use_accessors, irqdesc_states,
                             ARRAY_SIZE(irqdesc_states));
@@ -226,6 +227,15 @@ static const struct file_operations dfs_irq_ops = {
         .release        = single_release,
 };
 
+void irq_debugfs_copy_devname(int irq, struct device *dev)
+{
+        struct irq_desc *desc = irq_to_desc(irq);
+        const char *name = dev_name(dev);
+
+        if (name)
+                desc->dev_name = kstrdup(name, GFP_KERNEL);
+}
+
 void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *desc)
 {
         char name [10];
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index a4aa39009f0d..cfaec2669093 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -443,7 +443,9 @@ void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *desc);
 static inline void irq_remove_debugfs_entry(struct irq_desc *desc)
 {
         debugfs_remove(desc->debugfs_file);
+        kfree(desc->dev_name);
 }
+void irq_debugfs_copy_devname(int irq, struct device *dev);
 # ifdef CONFIG_IRQ_DOMAIN
 void irq_domain_debugfs_init(struct dentry *root);
 # else
@@ -458,4 +460,7 @@ static inline void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *d)
 static inline void irq_remove_debugfs_entry(struct irq_desc *d)
 {
 }
+static inline void irq_debugfs_copy_devname(int irq, struct device *dev)
+{
+}
 #endif /* CONFIG_GENERIC_IRQ_DEBUGFS */
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 3fa4bd59f569..94ecc0293844 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -16,6 +16,8 @@
 #include <linux/msi.h>
 #include <linux/slab.h>
 
+#include "internals.h"
+
 /**
  * alloc_msi_entry - Allocate an initialize msi_entry
  * @dev:        Pointer to the device for which this is allocated
@@ -373,8 +375,10 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
                         return ret;
                 }
 
-                for (i = 0; i < desc->nvec_used; i++)
+                for (i = 0; i < desc->nvec_used; i++) {
                         irq_set_msi_desc_off(virq, i, desc);
+                        irq_debugfs_copy_devname(virq + i, dev);
+                }
         }
 
         if (ops->msi_finish)