Re: [CFT] 4/6 (5): Add some locking to rsrc_mgr.c

From: Russell King (rmk@arm.linux.org.uk)
Date: Wed Mar 12 2003 - 16:01:13 EST


pcmcia-5.diff

  Add an element of locking to the resource manager - don't allow
  the PCMCIA resource lists to be changed while the pcmcia code is
  scanning them.

diff -ur orig/drivers/pcmcia/rsrc_mgr.c linux/drivers/pcmcia/rsrc_mgr.c
--- orig/drivers/pcmcia/rsrc_mgr.c Mon Nov 18 09:52:12 2002
+++ linux/drivers/pcmcia/rsrc_mgr.c Sat Mar 1 19:09:21 2003
@@ -85,6 +85,8 @@
 /* IO port resource database */
 static resource_map_t io_db = { 0, 0, &io_db };
 
+static DECLARE_MUTEX(rsrc_sem);
+
 #ifdef CONFIG_ISA
 
 typedef struct irq_info_t {
@@ -403,16 +405,20 @@
     static u_char order[] = { 0xd0, 0xe0, 0xc0, 0xf0 };
     static int hi = 0, lo = 0;
     u_long b, i, ok = 0;
-
- if (!probe_mem) return;
+
+ if (!probe_mem)
+ return;
+
+ down(&rsrc_sem);
     /* We do up to four passes through the list */
     if (!force_low) {
         if (hi++ || (inv_probe(is_valid, do_cksum, mem_db.next, s) > 0))
- return;
+ goto out;
         printk(KERN_NOTICE "cs: warning: no high memory space "
                "available!\n");
     }
- if (lo++) return;
+ if (lo++)
+ goto out;
     for (m = mem_db.next; m != &mem_db; m = n) {
         n = m->next;
         /* Only probe < 1 MB */
@@ -432,6 +438,8 @@
             }
         }
     }
+ out:
+ up(&rsrc_sem);
 }
 
 #else /* CONFIG_ISA */
@@ -442,11 +450,13 @@
     resource_map_t *m;
     static int done = 0;
     
- if (!probe_mem || done++)
- return;
- for (m = mem_db.next; m != &mem_db; m = m->next)
- if (do_mem_probe(m->base, m->num, is_valid, do_cksum, s))
- return;
+ if (probe_mem && done++ == 0) {
+ down(&rsrc_sem);
+ for (m = mem_db.next; m != &mem_db; m = m->next)
+ if (do_mem_probe(m->base, m->num, is_valid, do_cksum, s))
+ break;
+ up(&rsrc_sem);
+ }
 }
 
 #endif /* CONFIG_ISA */
@@ -469,7 +479,9 @@
 {
     ioaddr_t try;
     resource_map_t *m;
-
+ int ret = -1;
+
+ down(&rsrc_sem);
     for (m = io_db.next; m != &io_db; m = m->next) {
         try = (m->base & ~(align-1)) + *base;
         for (try = (try >= m->base) ? try : try+align;
@@ -477,12 +489,16 @@
              try += align) {
             if (request_io_resource(try, num, name, s->cap.cb_dev) == 0) {
                 *base = try;
- return 0;
+ ret = 0;
+ goto out;
             }
- if (!align) break;
+ if (!align)
+ break;
         }
     }
- return -1;
+ out:
+ up(&rsrc_sem);
+ return ret;
 }
 
 int find_mem_region(u_long *base, u_long num, u_long align,
@@ -490,26 +506,35 @@
 {
     u_long try;
     resource_map_t *m;
+ int ret = -1;
 
+ down(&rsrc_sem);
     while (1) {
         for (m = mem_db.next; m != &mem_db; m = m->next) {
             /* first pass >1MB, second pass <1MB */
- if ((force_low != 0) ^ (m->base < 0x100000)) continue;
+ if ((force_low != 0) ^ (m->base < 0x100000))
+ continue;
+
             try = (m->base & ~(align-1)) + *base;
             for (try = (try >= m->base) ? try : try+align;
                  (try >= m->base) && (try+num <= m->base+m->num);
                  try += align) {
                 if (request_mem_resource(try, num, name, s->cap.cb_dev) == 0) {
                     *base = try;
- return 0;
+ ret = 0;
+ goto out;
                 }
- if (!align) break;
+ if (!align)
+ break;
             }
         }
- if (force_low) break;
+ if (force_low)
+ break;
         force_low++;
     }
- return -1;
+ out:
+ up(&rsrc_sem);
+ return ret;
 }
 
 /*======================================================================
@@ -534,53 +559,75 @@
 int try_irq(u_int Attributes, int irq, int specific)
 {
     irq_info_t *info = &irq_table[irq];
+ int ret = 0;
+
+ down(&rsrc_sem);
     if (info->Attributes & RES_ALLOCATED) {
         switch (Attributes & IRQ_TYPE) {
         case IRQ_TYPE_EXCLUSIVE:
- return CS_IN_USE;
+ ret = CS_IN_USE;
+ break;
         case IRQ_TYPE_TIME:
             if ((info->Attributes & RES_IRQ_TYPE)
- != RES_IRQ_TYPE_TIME)
- return CS_IN_USE;
- if (Attributes & IRQ_FIRST_SHARED)
- return CS_BAD_ATTRIBUTE;
+ != RES_IRQ_TYPE_TIME) {
+ ret = CS_IN_USE;
+ break;
+ }
+ if (Attributes & IRQ_FIRST_SHARED) {
+ ret = CS_BAD_ATTRIBUTE;
+ break;
+ }
             info->Attributes |= RES_IRQ_TYPE_TIME | RES_ALLOCATED;
             info->time_share++;
             break;
         case IRQ_TYPE_DYNAMIC_SHARING:
             if ((info->Attributes & RES_IRQ_TYPE)
- != RES_IRQ_TYPE_DYNAMIC)
- return CS_IN_USE;
- if (Attributes & IRQ_FIRST_SHARED)
- return CS_BAD_ATTRIBUTE;
+ != RES_IRQ_TYPE_DYNAMIC) {
+ ret = CS_IN_USE;
+ break;
+ }
+ if (Attributes & IRQ_FIRST_SHARED) {
+ ret = CS_BAD_ATTRIBUTE;
+ break;
+ }
             info->Attributes |= RES_IRQ_TYPE_DYNAMIC | RES_ALLOCATED;
             info->dyn_share++;
             break;
         }
     } else {
- if ((info->Attributes & RES_RESERVED) && !specific)
- return CS_IN_USE;
- if (check_irq(irq) != 0)
- return CS_IN_USE;
+ if ((info->Attributes & RES_RESERVED) && !specific) {
+ ret = CS_IN_USE;
+ goto out;
+ }
+ if (check_irq(irq) != 0) {
+ ret = CS_IN_USE;
+ goto out;
+ }
         switch (Attributes & IRQ_TYPE) {
         case IRQ_TYPE_EXCLUSIVE:
             info->Attributes |= RES_ALLOCATED;
             break;
         case IRQ_TYPE_TIME:
- if (!(Attributes & IRQ_FIRST_SHARED))
- return CS_BAD_ATTRIBUTE;
+ if (!(Attributes & IRQ_FIRST_SHARED)) {
+ ret = CS_BAD_ATTRIBUTE;
+ break;
+ }
             info->Attributes |= RES_IRQ_TYPE_TIME | RES_ALLOCATED;
             info->time_share = 1;
             break;
         case IRQ_TYPE_DYNAMIC_SHARING:
- if (!(Attributes & IRQ_FIRST_SHARED))
- return CS_BAD_ATTRIBUTE;
+ if (!(Attributes & IRQ_FIRST_SHARED)) {
+ ret = CS_BAD_ATTRIBUTE;
+ break;
+ }
             info->Attributes |= RES_IRQ_TYPE_DYNAMIC | RES_ALLOCATED;
             info->dyn_share = 1;
             break;
         }
     }
- return 0;
+ out:
+ up(&rsrc_sem);
+ return ret;
 }
 
 #endif
@@ -594,6 +641,7 @@
     irq_info_t *info;
 
     info = &irq_table[irq];
+ down(&rsrc_sem);
     switch (Attributes & IRQ_TYPE) {
     case IRQ_TYPE_EXCLUSIVE:
         info->Attributes &= RES_RESERVED;
@@ -609,6 +657,7 @@
             info->Attributes &= RES_RESERVED;
         break;
     }
+ up(&rsrc_sem);
 }
 
 #endif
@@ -631,6 +680,8 @@
         return CS_BAD_SIZE;
 
     ret = CS_SUCCESS;
+
+ down(&rsrc_sem);
     switch (adj->Action) {
     case ADD_MANAGED_RESOURCE:
         ret = add_interval(&mem_db, base, num);
@@ -649,6 +700,7 @@
     default:
         ret = CS_UNSUPPORTED_FUNCTION;
     }
+ up(&rsrc_sem);
     
     return ret;
 }
@@ -657,7 +709,7 @@
 
 static int adjust_io(adjust_t *adj)
 {
- int base, num;
+ int base, num, ret = CS_SUCCESS;
     
     base = adj->resource.io.BasePort;
     num = adj->resource.io.NumPorts;
@@ -666,10 +718,13 @@
     if ((num <= 0) || (base+num > 0x10000) || (base+num <= base))
         return CS_BAD_SIZE;
 
+ down(&rsrc_sem);
     switch (adj->Action) {
     case ADD_MANAGED_RESOURCE:
- if (add_interval(&io_db, base, num) != 0)
- return CS_IN_USE;
+ if (add_interval(&io_db, base, num) != 0) {
+ ret = CS_IN_USE;
+ break;
+ }
 #ifdef CONFIG_ISA
         if (probe_io)
             do_io_probe(base, num);
@@ -679,17 +734,19 @@
         sub_interval(&io_db, base, num);
         break;
     default:
- return CS_UNSUPPORTED_FUNCTION;
+ ret = CS_UNSUPPORTED_FUNCTION;
         break;
     }
+ up(&rsrc_sem);
 
- return CS_SUCCESS;
+ return ret;
 }
 
 /*====================================================================*/
 
 static int adjust_irq(adjust_t *adj)
 {
+ int ret = CS_SUCCESS;
 #ifdef CONFIG_ISA
     int irq;
     irq_info_t *info;
@@ -698,33 +755,41 @@
     if ((irq < 0) || (irq > 15))
         return CS_BAD_IRQ;
     info = &irq_table[irq];
-
+
+ down(&rsrc_sem);
     switch (adj->Action) {
     case ADD_MANAGED_RESOURCE:
         if (info->Attributes & RES_REMOVED)
             info->Attributes &= ~(RES_REMOVED|RES_ALLOCATED);
         else
- if (adj->Attributes & RES_ALLOCATED)
- return CS_IN_USE;
+ if (adj->Attributes & RES_ALLOCATED) {
+ ret = CS_IN_USE;
+ break;
+ }
         if (adj->Attributes & RES_RESERVED)
             info->Attributes |= RES_RESERVED;
         else
             info->Attributes &= ~RES_RESERVED;
         break;
     case REMOVE_MANAGED_RESOURCE:
- if (info->Attributes & RES_REMOVED)
- return 0;
- if (info->Attributes & RES_ALLOCATED)
- return CS_IN_USE;
+ if (info->Attributes & RES_REMOVED) {
+ ret = 0;
+ break;
+ }
+ if (info->Attributes & RES_ALLOCATED) {
+ ret = CS_IN_USE;
+ break;
+ }
         info->Attributes |= RES_ALLOCATED|RES_REMOVED;
         info->Attributes &= ~RES_RESERVED;
         break;
     default:
- return CS_UNSUPPORTED_FUNCTION;
+ ret = CS_UNSUPPORTED_FUNCTION;
         break;
     }
+ up(&rsrc_sem);
 #endif
- return CS_SUCCESS;
+ return ret;
 }
 
 /*====================================================================*/

-- 
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html

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