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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 *property;
struct property *last_property = NULL; struct property *last_property = NULL;
struct cc_workarea *ccwa; struct cc_workarea *ccwa;
char *data_buf;
int cc_token; int cc_token;
int rc; int rc = -1;
cc_token = rtas_token("ibm,configure-connector"); cc_token = rtas_token("ibm,configure-connector");
if (cc_token == RTAS_UNKNOWN_SERVICE) if (cc_token == RTAS_UNKNOWN_SERVICE)
return NULL; return NULL;
spin_lock(&rtas_data_buf_lock); data_buf = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
ccwa = (struct cc_workarea *)&rtas_data_buf[0]; if (!data_buf)
return NULL;
ccwa = (struct cc_workarea *)&data_buf[0];
ccwa->drc_index = drc_index; ccwa->drc_index = drc_index;
ccwa->zero = 0; ccwa->zero = 0;
rc = rtas_call(cc_token, 2, 1, NULL, rtas_data_buf, NULL); do {
while (rc) { /* 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) { switch (rc) {
case NEXT_SIBLING: case NEXT_SIBLING:
dn = dlpar_parse_cc_node(ccwa); 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); "returned from configure-connector\n", rc);
goto cc_error; goto cc_error;
} }
} while (rc);
rc = rtas_call(cc_token, 2, 1, NULL, rtas_data_buf, NULL);
}
spin_unlock(&rtas_data_buf_lock);
return first_dn;
cc_error: cc_error:
if (first_dn) kfree(data_buf);
dlpar_free_cc_nodes(first_dn);
spin_unlock(&rtas_data_buf_lock); if (rc) {
return NULL; if (first_dn)
dlpar_free_cc_nodes(first_dn);
return NULL;
}
return first_dn;
} }
static struct device_node *derive_parent(const char *path) static struct device_node *derive_parent(const char *path)