powerpc/pseries: Correct rtas_data_buf locking in dlpar code
The dlpar code can cause a deadlock to occur when making the RTAS
configure-connector call. This occurs because we make kmalloc calls,
which can block, while parsing the rtas_data_buf and holding the
rtas_data_buf_lock. This an cause issues if someone else attempts
to grab the rtas_data_bug_lock.
This patch alleviates this issue by copying the contents of the rtas_data_buf
to a local buffer before parsing. This allows us to only hold the
rtas_data_buf_lock around the RTAS configure-connector calls.
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 227c1c3..72d8054 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -129,20 +129,35 @@
struct property *property;
struct property *last_property = NULL;
struct cc_workarea *ccwa;
+ char *data_buf;
int cc_token;
- int rc;
+ int rc = -1;
cc_token = rtas_token("ibm,configure-connector");
if (cc_token == RTAS_UNKNOWN_SERVICE)
return NULL;
- spin_lock(&rtas_data_buf_lock);
- ccwa = (struct cc_workarea *)&rtas_data_buf[0];
+ data_buf = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
+ if (!data_buf)
+ return NULL;
+
+ ccwa = (struct cc_workarea *)&data_buf[0];
ccwa->drc_index = drc_index;
ccwa->zero = 0;
- rc = rtas_call(cc_token, 2, 1, NULL, rtas_data_buf, NULL);
- while (rc) {
+ do {
+ /* Since we release the rtas_data_buf lock between configure
+ * connector calls we want to re-populate the rtas_data_buffer
+ * with the contents of the previous call.
+ */
+ spin_lock(&rtas_data_buf_lock);
+
+ memcpy(rtas_data_buf, data_buf, RTAS_DATA_BUF_SIZE);
+ rc = rtas_call(cc_token, 2, 1, NULL, rtas_data_buf, NULL);
+ memcpy(data_buf, rtas_data_buf, RTAS_DATA_BUF_SIZE);
+
+ spin_unlock(&rtas_data_buf_lock);
+
switch (rc) {
case NEXT_SIBLING:
dn = dlpar_parse_cc_node(ccwa);
@@ -197,18 +212,19 @@
"returned from configure-connector\n", rc);
goto cc_error;
}
-
- rc = rtas_call(cc_token, 2, 1, NULL, rtas_data_buf, NULL);
- }
-
- spin_unlock(&rtas_data_buf_lock);
- return first_dn;
+ } while (rc);
cc_error:
- if (first_dn)
- dlpar_free_cc_nodes(first_dn);
- spin_unlock(&rtas_data_buf_lock);
- return NULL;
+ kfree(data_buf);
+
+ if (rc) {
+ if (first_dn)
+ dlpar_free_cc_nodes(first_dn);
+
+ return NULL;
+ }
+
+ return first_dn;
}
static struct device_node *derive_parent(const char *path)