[PATCH] sym53c8xx_2 SMP deadlock on driver load

This patch fixes two problems with sym53c8xx_2.o in 2.4.x kernels:

1) A system hang when loading sym53c8xx_2.o on a SMP system with two
dual-channel LSI HBAs (http://bugzilla.kernel.org/show_bug.cgi?id=3680)

2) A function improperly marked __init.

Comment from Matthew Wilcox:
" This is a pretty ugly patch, but I think the three alternatives are
  worse:

   - Drop the iorl at the beginning of ->detect and reacquire it at exit.
     We don't know what else the iorl might be protecting.  Probably
     nothing, but I don't want to audit it.
   - Convert sym2 back to old error handling so the midlayer doesn't
     acquire the iorl for us in ->detect.
   - Acquire the iorl in ->release.  We might deadlock on something.

   So, sure, apply this patch. "

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>

diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c b/drivers/scsi/sym53c8xx_2/sym_glue.c
index ec16d44..fb69e1d 100644 (file)
--- a/drivers/scsi/sym53c8xx_2/sym_glue.c
+++ b/drivers/scsi/sym53c8xx_2/sym_glue.c
@@ -224,15 +224,26 @@ static u_long __init pci_map_mem(u_long base, u_long size)
 {
        u_long page_base        = ((u_long) base) & PAGE_MASK;
        u_long page_offs        = ((u_long) base) - page_base;
-       u_long page_remapped    = (u_long) ioremap(page_base, page_offs+size);
+       u_long page_remapped;
+
+       spin_unlock_irq(&io_request_lock);
+       page_remapped = (u_long) ioremap(page_base, page_offs+size);
+       spin_lock_irq(&io_request_lock);
 
        return page_remapped? (page_remapped + page_offs) : 0UL;
 }
 
-static void __init pci_unmap_mem(u_long vaddr, u_long size)
+static void pci_unmap_mem(u_long vaddr,
+                          u_long size,
+                          int holding_io_request_lock)
 {
-       if (vaddr)
+       if (vaddr) {
+               if (holding_io_request_lock)
+                       spin_unlock_irq(&io_request_lock);
                iounmap((void *) (vaddr & PAGE_MASK));
+               if (holding_io_request_lock)
+                       spin_lock_irq(&io_request_lock);
+       }
 }
 #endif
 
@@ -1840,7 +1851,7 @@ static int sym53c8xx_proc_info(char *buffer, char **start, off_t offset,
 /*
  *     Free controller resources.
  */
-static void sym_free_resources(hcb_p np)
+static void sym_free_resources(hcb_p np, int holding_io_request_lock)
 {
        /*
         *  Free O/S specific resources.
@@ -1851,9 +1862,13 @@ static void sym_free_resources(hcb_p np)
                release_region(np->s.io_port, np->s.io_ws);
 #ifndef SYM_OPT_NO_BUS_MEMORY_MAPPING
        if (np->s.mmio_va)
-               pci_unmap_mem(np->s.mmio_va, np->s.io_ws);
+               pci_unmap_mem(np->s.mmio_va,
+                             np->s.io_ws,
+                             holding_io_request_lock);
        if (np->s.ram_va)
-               pci_unmap_mem(np->s.ram_va, np->ram_ws);
+               pci_unmap_mem(np->s.ram_va,
+                             np->ram_ws,
+                             holding_io_request_lock);
 #endif
        /*
         *  Free O/S independant resources.
@@ -2155,7 +2170,7 @@ attach_failed:
        if (!instance) return -1;
        printf_info("%s: giving up ...\n", sym_name(np));
        if (np)
-               sym_free_resources(np);
+               sym_free_resources(np, 1);
        scsi_unregister(instance);
 
         return -1;
@@ -2197,7 +2212,7 @@ static void __init sym_get_nvram(sym_device *devp, sym_nvram *nvp)
 #ifdef SYM_CONF_IOMAPPED
        release_region(devp->s.io_port, 128);
 #else
-       pci_unmap_mem((u_long) devp->s.mmio_va, 128ul);
+       pci_unmap_mem((u_long) devp->s.mmio_va, 128ul, 1);
 #endif
 }
 #endif /* SYM_CONF_NVRAM_SUPPORT */
@@ -2551,7 +2566,7 @@ sym53c8xx_pci_init(Scsi_Host_Template *tpnt, pcidev_t pdev, sym_device *device)
                ram_ptr = pci_map_mem(base_2_c, ram_size);
                if (ram_ptr) {
                        ram_val = readl_raw(ram_ptr + ram_size - 16);
-                       pci_unmap_mem(ram_ptr, ram_size);
+                       pci_unmap_mem(ram_ptr, ram_size, 1);
                        if (ram_val == 0x52414944) {
                                printf_info("%s: not initializing, "
                                            "driven by RAID controller.\n",
@@ -2980,7 +2995,7 @@ static int sym_detach(hcb_p np)
        /*
         *  Free host resources
         */
-       sym_free_resources(np);
+       sym_free_resources(np, 0);
 
        return 1;
 }