mtd: phram: dot not crash when built-in and passing boot param
This patch is based on Ville Herva's similar patch to block2mtd.
Trying to pass a parameter through the kernel command line when built-in would
crash the kernel, as phram_setup() was called so early that kmalloc() was not
functional yet.
This patch only saves the parameter string at the early boot stage, and parses
it later when init_phram() is called. The same happens in both module and
built-in cases.
With this patch, I can boot with a statically-compiled phram, and mount a
ext2 root fs from physical RAM, without the need for a initrd.
This has been tested in built-in and module cases, with and without a
parameter string.
Artem: amended comments a bit
Signed-off-by: Hervé Fache <h-fache@ti.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
index 9d2bf17..3d91ace 100644
--- a/drivers/mtd/devices/phram.c
+++ b/drivers/mtd/devices/phram.c
@@ -39,7 +39,8 @@
memset(start + instr->addr, 0xff, instr->len);
- /* This'll catch a few races. Free the thing before returning :)
+ /*
+ * This'll catch a few races. Free the thing before returning :)
* I don't feel at all ashamed. This kind of thing is possible anyway
* with flash, but unlikely.
*/
@@ -204,7 +205,17 @@
return 1; \
} while (0)
-static int phram_setup(const char *val, struct kernel_param *kp)
+/*
+ * This shall contain the module parameter if any. It is of the form:
+ * - phram=<device>,<address>,<size> for module case
+ * - phram.phram=<device>,<address>,<size> for built-in case
+ * We leave 64 bytes for the device name, 12 for the address and 12 for the
+ * size.
+ * Example: phram.phram=rootfs,0xa0000000,512Mi
+ */
+static __initdata char phram_paramline[64+12+12];
+
+static int phram_setup(const char *val)
{
char buf[64+12+12], *str = buf;
char *token[3];
@@ -253,12 +264,28 @@
return ret;
}
-module_param_call(phram, phram_setup, NULL, NULL, 000);
+static int __init phram_param_call(const char *val, struct kernel_param *kp)
+{
+ /*
+ * This function is always called before 'init_phram()', whether
+ * built-in or module.
+ */
+ if (strlen(val) >= sizeof(phram_paramline))
+ return -ENOSPC;
+ strcpy(phram_paramline, val);
+
+ return 0;
+}
+
+module_param_call(phram, phram_param_call, NULL, NULL, 000);
MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");
static int __init init_phram(void)
{
+ if (phram_paramline[0])
+ return phram_setup(phram_paramline);
+
return 0;
}