[PATCH] osmo-bts[master]: Fix race condition in attribute reporting

Max gerrit-no-reply at lists.osmocom.org
Thu Oct 12 12:03:49 UTC 2017


Review at  https://gerrit.osmocom.org/4232

Fix race condition in attribute reporting

Previously it could be possible that the attribute request comes from
BSC before the TRX is properly initialized which would lead to SIGABRT
caused by OSMO_ASSERT() in PHY instantiation. Workaround this by
explicitly checking for TRX availability before handling TRX-specific
attributes.

This only happens with osmo-bts-trx and is hard to reproduce. Ideal fix
would be to defer attribute response until we have TRX connected but
that would make corresponding code more complex because we'll need to
save the attribute request and properly hook response routine into TRX
connection handler. Alternatively we can postpone osmo-bts-trx
connection to BSC until TRX is available: it's not very useful without
it anyway.

Change-Id: Id36885e507c4a3203b5662c0fde12c5206174d82
Fixes: OS#2560
---
M src/common/oml.c
1 file changed, 12 insertions(+), 2 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/32/4232/1

diff --git a/src/common/oml.c b/src/common/oml.c
index 69a2642..2d1c862 100644
--- a/src/common/oml.c
+++ b/src/common/oml.c
@@ -209,19 +209,29 @@
 {
 	uint16_t i, attr_out_index = 1; /* byte 0 is reserved for unsupported attributes counter */
 	struct msgb *attr_buf = oml_msgb_alloc();
+	bool processed;
 
 	if (!attr_buf)
 		return -ENOMEM;
 
 	for (i = 0; i < attr_len; i++) {
+		processed = false;
 		switch (attr[i]) {
 		case NM_ATT_SW_CONFIG:
-			add_trx_attr(attr_buf, trx);
+			if (trx) {
+				add_trx_attr(attr_buf, trx);
+				processed = true;
+			} else
+				LOGP(DOML, LOGL_ERROR, "O&M Get Attributes [%u], %s is unhandled due to missing TRX.\n",
+				     i, get_value_string(abis_nm_att_names, attr[i]));
 			break;
 		default:
 			LOGP(DOML, LOGL_ERROR, "O&M Get Attributes [%u], %s is unsupported by TRX.\n", i,
 			     get_value_string(abis_nm_att_names, attr[i]));
-			out[attr_out_index] = attr[i]; /* assemble values of supported attributes and list of unsupported ones */
+		}
+		/* assemble values of supported attributes and list of unsupported ones */
+		if (!processed) {
+			out[attr_out_index] = attr[i]; 
 			attr_out_index++;
 		}
 	}

-- 
To view, visit https://gerrit.osmocom.org/4232
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Id36885e507c4a3203b5662c0fde12c5206174d82
Gerrit-PatchSet: 1
Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Owner: Max <msuraev at sysmocom.de>


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