net/mlx: fix rdma-core glue path with EAL plugins

Glue object files are looked up in RTE_EAL_PMD_PATH by default when set and
should be installed in this directory.

During startup, EAL attempts to load them automatically like other plug-ins
found there. While normally harmless, dlopen() fails when rdma-core is not
installed, EAL interprets this as a fatal error and terminates the
application.

This patch requests glue objects to be installed in a different directory
to prevent their automatic loading by EAL since they are PMD helpers, not
actual DPDK plug-ins.

Fixes: f6242d0655cd ("net/mlx: make rdma-core glue path configurable")
Cc: stable@dpdk.org
Reported-by: Timothy Redaelli <tredaelli@redhat.com>
Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Tested-by: Timothy Redaelli <tredaelli@redhat.com>

diff --git a/doc/guides/nics/mlx4.rst b/doc/guides/nics/mlx4.rst
index 98b9716..afeff27 100644 (file)
--- a/doc/guides/nics/mlx4.rst
+++ b/doc/guides/nics/mlx4.rst
@@ -98,9 +98,10 @@ These options can be modified in the ``.config`` file.
   missing with ``ldd(1)``.
 
   It works by moving these dependencies to a purpose-built rdma-core "glue"
-  plug-in, which must either be installed in ``CONFIG_RTE_EAL_PMD_PATH`` if
-  set, or in a standard location for the dynamic linker (e.g. ``/lib``) if
-  left to the default empty string (``""``).
+  plug-in which must either be installed in a directory whose name is based
+  on ``CONFIG_RTE_EAL_PMD_PATH`` suffixed with ``-glue`` if set, or in a
+  standard location for the dynamic linker (e.g. ``/lib``) if left to the
+  default empty string (``""``).
 
   This option has no performance impact.
 

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index 0e6e525..46d26e4 100644 (file)
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -171,9 +171,10 @@ These options can be modified in the ``.config`` file.
   missing with ``ldd(1)``.
 
   It works by moving these dependencies to a purpose-built rdma-core "glue"
-  plug-in, which must either be installed in ``CONFIG_RTE_EAL_PMD_PATH`` if
-  set, or in a standard location for the dynamic linker (e.g. ``/lib``) if
-  left to the default empty string (``""``).
+  plug-in which must either be installed in a directory whose name is based
+  on ``CONFIG_RTE_EAL_PMD_PATH`` suffixed with ``-glue`` if set, or in a
+  standard location for the dynamic linker (e.g. ``/lib``) if left to the
+  default empty string (``""``).
 
   This option has no performance impact.
 

diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index ee93daf..fb8a8b8 100644 (file)
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -707,12 +707,54 @@ static struct rte_pci_driver mlx4_driver = {
 
 #ifdef RTE_LIBRTE_MLX4_DLOPEN_DEPS
 
+/**
+ * Suffix RTE_EAL_PMD_PATH with "-glue".
+ *
+ * This function performs a sanity check on RTE_EAL_PMD_PATH before
+ * suffixing its last component.
+ *
+ * @param buf[out]
+ *   Output buffer, should be large enough otherwise NULL is returned.
+ * @param size
+ *   Size of @p out.
+ *
+ * @return
+ *   Pointer to @p buf or @p NULL in case suffix cannot be appended.
+ */
+static char *
+mlx4_glue_path(char *buf, size_t size)
+{
+       static const char *const bad[] = { "/", ".", "..", NULL };
+       const char *path = RTE_EAL_PMD_PATH;
+       size_t len = strlen(path);
+       size_t off;
+       int i;
+
+       while (len && path[len - 1] == '/')
+               --len;
+       for (off = len; off && path[off - 1] != '/'; --off)
+               ;
+       for (i = 0; bad[i]; ++i)
+               if (!strncmp(path + off, bad[i], (int)(len - off)))
+                       goto error;
+       i = snprintf(buf, size, "%.*s-glue", (int)len, path);
+       if (i == -1 || (size_t)i >= size)
+               goto error;
+       return buf;
+error:
+       ERROR("unable to append \"-glue\" to last component of"
+             " RTE_EAL_PMD_PATH (\"" RTE_EAL_PMD_PATH "\"),"
+             " please re-configure DPDK");
+       return NULL;
+}
+
 /**
  * Initialization routine for run-time dependency on rdma-core.
  */
 static int
 mlx4_glue_init(void)
 {
+       char glue_path[sizeof(RTE_EAL_PMD_PATH) - 1 + sizeof("-glue")];
        const char *path[] = {
                /*
                 * A basic security check is necessary before trusting
@@ -720,7 +762,13 @@ mlx4_glue_init(void)
                 */
                (geteuid() == getuid() && getegid() == getgid() ?
                 getenv("MLX4_GLUE_PATH") : NULL),
-               RTE_EAL_PMD_PATH,
+               /*
+                * When RTE_EAL_PMD_PATH is set, use its glue-suffixed
+                * variant, otherwise let dlopen() look up libraries on its
+                * own.
+                */
+               (*RTE_EAL_PMD_PATH ?
+                mlx4_glue_path(glue_path, sizeof(glue_path)) : ""),
        };
        unsigned int i = 0;
        void *handle = NULL;

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 61cb931..0ca16d1 100644 (file)
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -1042,12 +1042,54 @@ static struct rte_pci_driver mlx5_driver = {
 
 #ifdef RTE_LIBRTE_MLX5_DLOPEN_DEPS
 
+/**
+ * Suffix RTE_EAL_PMD_PATH with "-glue".
+ *
+ * This function performs a sanity check on RTE_EAL_PMD_PATH before
+ * suffixing its last component.
+ *
+ * @param buf[out]
+ *   Output buffer, should be large enough otherwise NULL is returned.
+ * @param size
+ *   Size of @p out.
+ *
+ * @return
+ *   Pointer to @p buf or @p NULL in case suffix cannot be appended.
+ */
+static char *
+mlx5_glue_path(char *buf, size_t size)
+{
+       static const char *const bad[] = { "/", ".", "..", NULL };
+       const char *path = RTE_EAL_PMD_PATH;
+       size_t len = strlen(path);
+       size_t off;
+       int i;
+
+       while (len && path[len - 1] == '/')
+               --len;
+       for (off = len; off && path[off - 1] != '/'; --off)
+               ;
+       for (i = 0; bad[i]; ++i)
+               if (!strncmp(path + off, bad[i], (int)(len - off)))
+                       goto error;
+       i = snprintf(buf, size, "%.*s-glue", (int)len, path);
+       if (i == -1 || (size_t)i >= size)
+               goto error;
+       return buf;
+error:
+       ERROR("unable to append \"-glue\" to last component of"
+             " RTE_EAL_PMD_PATH (\"" RTE_EAL_PMD_PATH "\"),"
+             " please re-configure DPDK");
+       return NULL;
+}
+
 /**
  * Initialization routine for run-time dependency on rdma-core.
  */
 static int
 mlx5_glue_init(void)
 {
+       char glue_path[sizeof(RTE_EAL_PMD_PATH) - 1 + sizeof("-glue")];
        const char *path[] = {
                /*
                 * A basic security check is necessary before trusting
@@ -1055,7 +1097,13 @@ mlx5_glue_init(void)
                 */
                (geteuid() == getuid() && getegid() == getgid() ?
                 getenv("MLX5_GLUE_PATH") : NULL),
-               RTE_EAL_PMD_PATH,
+               /*
+                * When RTE_EAL_PMD_PATH is set, use its glue-suffixed
+                * variant, otherwise let dlopen() look up libraries on its
+                * own.
+                */
+               (*RTE_EAL_PMD_PATH ?
+                mlx5_glue_path(glue_path, sizeof(glue_path)) : ""),
        };
        unsigned int i = 0;
        void *handle = NULL;