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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>
This commit is contained in:
Nathan Fontenot 2010-08-18 09:58:46 +00:00 committed by Benjamin Herrenschmidt
parent a28dec2f26
commit 93f68f1ef7
1 changed files with 31 additions and 15 deletions
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46
arch/powerpc/platforms/pseries/dlpar.c
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@ -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;
}
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)