parisc: ensure broadcast tlb purge runs single threaded

The TLB flushing functions on hppa, which causes PxTLB broadcasts on the system
bus, needs to be protected by irq-safe spinlocks to avoid irq handlers to deadlock
the kernel. The deadlocks only happened during I/O intensive loads and triggered
pretty seldom, which is why this bug went so long unnoticed.

Signed-off-by: Helge Deller <deller@gmx.de>
[edited to use spin_lock_irqsave on UP as well since we'd been locking there
 all this time anyway, --kyle]
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

3 files changed, 30 insertions, 19 deletions

diff --git a/arch/parisc/include/asm/tlbflush.h b/arch/parisc/include/asm/tlbflush.h
index 1f6fd4fc05b9..8f1a8100bf2d 100644
--- a/arch/parisc/include/asm/tlbflush.h
+++ b/arch/parisc/include/asm/tlbflush.h
@@ -12,14 +12,12 @@
  * N class systems, only one PxTLB inter processor broadcast can be
  * active at any one time on the Merced bus.  This tlb purge
  * synchronisation is fairly lightweight and harmless so we activate
- * it on all SMP systems not just the N class.  We also need to have
- * preemption disabled on uniprocessor machines, and spin_lock does that
- * nicely.
+ * it on all systems not just the N class.
  */
 extern spinlock_t pa_tlb_lock;
 
-#define purge_tlb_start(x) spin_lock(&pa_tlb_lock)
-#define purge_tlb_end(x) spin_unlock(&pa_tlb_lock)
+#define purge_tlb_start(flags)  spin_lock_irqsave(&pa_tlb_lock, flags)
+#define purge_tlb_end(flags)    spin_unlock_irqrestore(&pa_tlb_lock, flags)
 
 extern void flush_tlb_all(void);
 extern void flush_tlb_all_local(void *);
@@ -63,14 +61,16 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
 static inline void flush_tlb_page(struct vm_area_struct *vma,
         unsigned long addr)
 {
+        unsigned long flags;
+
         /* For one page, it's not worth testing the split_tlb variable */
 
         mb();
         mtsp(vma->vm_mm->context,1);
-        purge_tlb_start();
+        purge_tlb_start(flags);
         pdtlb(addr);
         pitlb(addr);
-        purge_tlb_end();
+        purge_tlb_end(flags);
 }
 
 void __flush_tlb_range(unsigned long sid,
diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index f34082da009a..b6ed34de14e1 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -397,12 +397,13 @@ EXPORT_SYMBOL(flush_kernel_icache_range_asm);
 
 void clear_user_page_asm(void *page, unsigned long vaddr)
 {
+        unsigned long flags;
         /* This function is implemented in assembly in pacache.S */
         extern void __clear_user_page_asm(void *page, unsigned long vaddr);
 
-        purge_tlb_start();
+        purge_tlb_start(flags);
         __clear_user_page_asm(page, vaddr);
-        purge_tlb_end();
+        purge_tlb_end(flags);
 }
 
 #define FLUSH_THRESHOLD 0x80000 /* 0.5MB */
@@ -443,20 +444,24 @@ extern void clear_user_page_asm(void *page, unsigned long vaddr);
 
 void clear_user_page(void *page, unsigned long vaddr, struct page *pg)
 {
+        unsigned long flags;
+
         purge_kernel_dcache_page((unsigned long)page);
-        purge_tlb_start();
+        purge_tlb_start(flags);
         pdtlb_kernel(page);
-        purge_tlb_end();
+        purge_tlb_end(flags);
         clear_user_page_asm(page, vaddr);
 }
 EXPORT_SYMBOL(clear_user_page);
 
 void flush_kernel_dcache_page_addr(void *addr)
 {
+        unsigned long flags;
+
         flush_kernel_dcache_page_asm(addr);
-        purge_tlb_start();
+        purge_tlb_start(flags);
         pdtlb_kernel(addr);
-        purge_tlb_end();
+        purge_tlb_end(flags);
 }
 EXPORT_SYMBOL(flush_kernel_dcache_page_addr);
 
@@ -489,8 +494,10 @@ void __flush_tlb_range(unsigned long sid, unsigned long start,
         if (npages >= 512)  /* 2MB of space: arbitrary, should be tuned */
                 flush_tlb_all();
         else {
+                unsigned long flags;
+
                 mtsp(sid, 1);
-                purge_tlb_start();
+                purge_tlb_start(flags);
                 if (split_tlb) {
                         while (npages--) {
                                 pdtlb(start);
@@ -503,7 +510,7 @@ void __flush_tlb_range(unsigned long sid, unsigned long start,
                                 start += PAGE_SIZE;
                         }
                 }
-                purge_tlb_end();
+                purge_tlb_end(flags);
         }
 }
 
diff --git a/arch/parisc/kernel/pci-dma.c b/arch/parisc/kernel/pci-dma.c
index 7d927eac932b..c07f618ff7da 100644
--- a/arch/parisc/kernel/pci-dma.c
+++ b/arch/parisc/kernel/pci-dma.c
@@ -90,12 +90,14 @@ static inline int map_pte_uncached(pte_t * pte,
         if (end > PMD_SIZE)
                 end = PMD_SIZE;
         do {
+                unsigned long flags;
+
                 if (!pte_none(*pte))
                         printk(KERN_ERR "map_pte_uncached: page already exists\n");
                 set_pte(pte, __mk_pte(*paddr_ptr, PAGE_KERNEL_UNC));
-                purge_tlb_start();
+                purge_tlb_start(flags);
                 pdtlb_kernel(orig_vaddr);
-                purge_tlb_end();
+                purge_tlb_end(flags);
                 vaddr += PAGE_SIZE;
                 orig_vaddr += PAGE_SIZE;
                 (*paddr_ptr) += PAGE_SIZE;
@@ -168,11 +170,13 @@ static inline void unmap_uncached_pte(pmd_t * pmd, unsigned long vaddr,
         if (end > PMD_SIZE)
                 end = PMD_SIZE;
         do {
+                unsigned long flags;
                 pte_t page = *pte;
+
                 pte_clear(&init_mm, vaddr, pte);
-                purge_tlb_start();
+                purge_tlb_start(flags);
                 pdtlb_kernel(orig_vaddr);
-                purge_tlb_end();
+                purge_tlb_end(flags);
                 vaddr += PAGE_SIZE;
                 orig_vaddr += PAGE_SIZE;
                 pte++;