Re: [PATCH] pcmcia driver model support [4/5]

From: Russell King
Date: Mon Aug 23 2004 - 13:27:04 EST


On Mon, Aug 23, 2004 at 07:05:39PM +0100, Russell King wrote:
> On Thu, Aug 05, 2004 at 10:28:20PM +0000, Adam Belay wrote:
> >...
> > The event is then eventually reported to the ds.c client. DS then informs
> > userspace of the ejection request and waits for userspace to reply with whether
> > the request was successful. pcmcia-cs, in turn, calls DS_GET_FIRST_TUPLE while
> > verifying the ejection request.
>
> The alternative is that we avoid taking the lock when we know that
> we don't need to re-validate the regions. How does this look?

Terrible. 8) This one probably builds.

(Note: I'm expecting that this patch will have offsets, but should
still apply, build and should solve your problem.)

--- linux-2.6-pcmcia/drivers/pcmcia/rsrc_mgr.c Sun Aug 22 15:42:36 2004
+++ linux/drivers/pcmcia/rsrc_mgr.c Mon Aug 23 19:11:40 2004
@@ -88,6 +88,9 @@
};

static DECLARE_MUTEX(rsrc_sem);
+static unsigned int rsrc_mem_probe;
+#define MEM_PROBE_LOW (1 << 0)
+#define MEM_PROBE_HIGH (1 << 1)

#ifdef CONFIG_PCMCIA_PROBE

@@ -451,24 +454,22 @@
return do_mem_probe(m->base, m->num, s);
}

-static void validate_mem(struct pcmcia_socket *s)
+static void validate_mem(struct pcmcia_socket *s, unsigned int probe_mask)
{
resource_map_t *m, mm;
static u_char order[] = { 0xd0, 0xe0, 0xc0, 0xf0 };
static int hi = 0, lo = 0;
u_long b, i, ok = 0;
- int force_low = !(s->features & SS_CAP_PAGE_REGS);

- down(&rsrc_sem);
/* We do up to four passes through the list */
- if (!force_low) {
- if (hi++ || (inv_probe(mem_db.next, s) > 0))
- goto out;
+ if (probe_mask & MEM_PROBE_HIGH) {
+ if (inv_probe(mem_db.next, s) > 0)
+ return;
printk(KERN_NOTICE "cs: warning: no high memory space "
"available!\n");
}
- if (lo++)
- goto out;
+ if ((probe_mask & MEM_PROBE_LOW) == 0)
+ return;
for (m = mem_db.next; m != &mem_db; m = mm.next) {
mm = *m;
/* Only probe < 1 MB */
@@ -488,38 +489,51 @@
}
}
}
- out:
- up(&rsrc_sem);
}

#else /* CONFIG_PCMCIA_PROBE */

-static void validate_mem(struct pcmcia_socket *s)
+static void validate_mem(struct pcmcia_socket *s, unsigned int probe_mask)
{
- resource_map_t *m, mm;
- static int done = 0;
+ resource_map_t *m, mm;

- if (done++ == 0) {
- down(&rsrc_sem);
for (m = mem_db.next; m != &mem_db; m = mm.next) {
- mm = *m;
- if (do_mem_probe(mm.base, mm.num, s))
- break;
+ mm = *m;
+ if (do_mem_probe(mm.base, mm.num, s))
+ break;
}
- up(&rsrc_sem);
- }
}

#endif /* CONFIG_PCMCIA_PROBE */

+/*
+ * Locking note: this is the only place where we take
+ * both rsrc_sem and skt_sem.
+ */
void pcmcia_validate_mem(struct pcmcia_socket *s)
{
- down(&s->skt_sem);
+ if (probe_mem) {
+ unsigned int probe_mask;
+
+ down(&rsrc_sem);
+
+ probe_mask = MEM_PROBE_LOW;
+ if (s->features & SS_CAP_PAGE_REGS)
+ probe_mask = MEM_PROBE_HIGH;

- if (probe_mem && s->state & SOCKET_PRESENT)
- validate_mem(s);
+ if (probe_mask & ~rsrc_mem_probe) {
+ rsrc_mem_probe |= probe_mask;

- up(&s->skt_sem);
+ down(&s->skt_sem);
+
+ if (s->state & SOCKET_PRESENT)
+ validate_mem(s, probe_mask);
+
+ up(&s->skt_sem);
+ }
+
+ up(&rsrc_sem);
+ }
}

EXPORT_SYMBOL(pcmcia_validate_mem);


--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
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