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authorNathan Fontenot <nfont@austin.ibm.com>2010-08-18 09:58:46 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2010-09-02 10:07:38 +1000
commit93f68f1ef787d97ab688f78a01f446e85bb9a496 (patch)
tree48686ab3564991aba66e47f1a6048ff8a4cbe4c2 /arch
parenta28dec2f26013aad89446b1f708f948617bc28a2 (diff)
downloadlinux-linaro-android-93f68f1ef787d97ab688f78a01f446e85bb9a496.tar.gz
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/platforms/pseries/dlpar.c42
1 files changed, 29 insertions, 13 deletions
diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 227c1c3d585..72d8054fa73 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -129,20 +129,35 @@ struct device_node *dlpar_configure_connector(u32 drc_index)
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 @@ struct device_node *dlpar_configure_connector(u32 drc_index)
"returned from configure-connector\n", rc);
goto cc_error;
}
+ } while (rc);
- rc = rtas_call(cc_token, 2, 1, NULL, rtas_data_buf, NULL);
+cc_error:
+ kfree(data_buf);
+
+ if (rc) {
+ if (first_dn)
+ dlpar_free_cc_nodes(first_dn);
+
+ return NULL;
}
- spin_unlock(&rtas_data_buf_lock);
return first_dn;
-
-cc_error:
- if (first_dn)
- dlpar_free_cc_nodes(first_dn);
- spin_unlock(&rtas_data_buf_lock);
- return NULL;
}
static struct device_node *derive_parent(const char *path)