fix: handle EINTR correctly in get_cpu_mask_from_sysfs

If the read() in get_cpu_mask_from_sysfs() fails with EINTR, the code is
supposed to retry, but the while loop condition has (bytes_read > 0),
which is false when read() fails with EINTR. The result is that the code
exits the loop, having only read part of the string.

Use (bytes_read != 0) in the while loop condition instead, since the
(bytes_read < 0) case is already handled in the loop.

Original fix in liburcu from Benjamin Marzinski <bmarzins@redhat.com>:

  commit 9922f33e2986 ("fix: handle EINTR correctly in get_cpu_mask_from_sysfs")

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I885a0fb98e5a7cfb9a8bd180c8e64b20926ff58c

diff --git a/libringbuffer/smp.c b/libringbuffer/smp.c
index 73804b66427f409626b532d1b1e12b01f5f124ff..8a65c40568b2483cd82c2a010c88c7c5155c4ecc 100644 (file)
--- a/libringbuffer/smp.c
+++ b/libringbuffer/smp.c
@@ -142,7 +142,7 @@ int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes)
 
                total_bytes_read += bytes_read;
                assert(total_bytes_read <= max_bytes);
-       } while (max_bytes > total_bytes_read && bytes_read > 0);
+       } while (max_bytes > total_bytes_read && bytes_read != 0);
 
        /*
         * Make sure the mask read is a null terminated string.