net/mlx: make rdma-core glue path configurable

Since rdma-core glue libraries are intrinsically tied to their respective
PMDs and used as internal plug-ins, their presence in the default search
path among other system libraries for the dynamic linker is not necessarily
desired.

This commit enables their installation and subsequent look-up at run time
in RTE_EAL_PMD_PATH if configured to a nonempty string. This path can also
be overridden by environment variables MLX[45]_GLUE_PATH.

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

diff --git a/doc/guides/nics/mlx4.rst b/doc/guides/nics/mlx4.rst
index 13cc6ec..98b9716 100644 (file)
--- a/doc/guides/nics/mlx4.rst
+++ b/doc/guides/nics/mlx4.rst
@@ -97,6 +97,11 @@ These options can be modified in the ``.config`` file.
   ``CONFIG_RTE_BUILD_SHARED_LIB`` disabled) and they won't show up as
   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 (``""``).
+
   This option has no performance impact.
 
 - ``CONFIG_RTE_LIBRTE_MLX4_DEBUG`` (default **n**)
@@ -113,6 +118,18 @@ These options can be modified in the ``.config`` file.
 
   This value is always 1 for RX queues since they use a single MP.
 
+Environment variables
+~~~~~~~~~~~~~~~~~~~~~
+
+- ``MLX4_GLUE_PATH``
+
+  A list of directories in which to search for the rdma-core "glue" plug-in,
+  separated by colons or semi-colons.
+
+  Only matters when compiled with ``CONFIG_RTE_LIBRTE_MLX4_DLOPEN_DEPS``
+  enabled and most useful when ``CONFIG_RTE_EAL_PMD_PATH`` is also set,
+  since ``LD_LIBRARY_PATH`` has no effect in this case.
+
 Run-time configuration
 ~~~~~~~~~~~~~~~~~~~~~~
 

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index d54ff76..0e6e525 100644 (file)
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -170,6 +170,11 @@ These options can be modified in the ``.config`` file.
   ``CONFIG_RTE_BUILD_SHARED_LIB`` disabled) and they won't show up as
   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 (``""``).
+
   This option has no performance impact.
 
 - ``CONFIG_RTE_LIBRTE_MLX5_DEBUG`` (default **n**)
@@ -189,6 +194,15 @@ These options can be modified in the ``.config`` file.
 Environment variables
 ~~~~~~~~~~~~~~~~~~~~~
 
+- ``MLX5_GLUE_PATH``
+
+  A list of directories in which to search for the rdma-core "glue" plug-in,
+  separated by colons or semi-colons.
+
+  Only matters when compiled with ``CONFIG_RTE_LIBRTE_MLX5_DLOPEN_DEPS``
+  enabled and most useful when ``CONFIG_RTE_EAL_PMD_PATH`` is also set,
+  since ``LD_LIBRARY_PATH`` has no effect in this case.
+
 - ``MLX5_PMD_ENABLE_PADDING``
 
   Enables HW packet padding in PCI bus transactions.

diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index a76fc59..ee93daf 100644 (file)
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -713,11 +713,52 @@ static struct rte_pci_driver mlx4_driver = {
 static int
 mlx4_glue_init(void)
 {
+       const char *path[] = {
+               /*
+                * A basic security check is necessary before trusting
+                * MLX4_GLUE_PATH, which may override RTE_EAL_PMD_PATH.
+                */
+               (geteuid() == getuid() && getegid() == getgid() ?
+                getenv("MLX4_GLUE_PATH") : NULL),
+               RTE_EAL_PMD_PATH,
+       };
+       unsigned int i = 0;
        void *handle = NULL;
        void **sym;
        const char *dlmsg;
 
-       handle = dlopen(MLX4_GLUE, RTLD_LAZY);
+       while (!handle && i != RTE_DIM(path)) {
+               const char *end;
+               size_t len;
+               int ret;
+
+               if (!path[i]) {
+                       ++i;
+                       continue;
+               }
+               end = strpbrk(path[i], ":;");
+               if (!end)
+                       end = path[i] + strlen(path[i]);
+               len = end - path[i];
+               ret = 0;
+               do {
+                       char name[ret + 1];
+
+                       ret = snprintf(name, sizeof(name), "%.*s%s" MLX4_GLUE,
+                                      (int)len, path[i],
+                                      (!len || *(end - 1) == '/') ? "" : "/");
+                       if (ret == -1)
+                               break;
+                       if (sizeof(name) != (size_t)ret + 1)
+                               continue;
+                       DEBUG("looking for rdma-core glue as \"%s\"", name);
+                       handle = dlopen(name, RTLD_LAZY);
+                       break;
+               } while (1);
+               path[i] = end + 1;
+               if (!*end)
+                       ++i;
+       }
        if (!handle) {
                rte_errno = EINVAL;
                dlmsg = dlerror();

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 53182aa..d62c747 100644 (file)
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -1056,11 +1056,52 @@ static struct rte_pci_driver mlx5_driver = {
 static int
 mlx5_glue_init(void)
 {
+       const char *path[] = {
+               /*
+                * A basic security check is necessary before trusting
+                * MLX5_GLUE_PATH, which may override RTE_EAL_PMD_PATH.
+                */
+               (geteuid() == getuid() && getegid() == getgid() ?
+                getenv("MLX5_GLUE_PATH") : NULL),
+               RTE_EAL_PMD_PATH,
+       };
+       unsigned int i = 0;
        void *handle = NULL;
        void **sym;
        const char *dlmsg;
 
-       handle = dlopen(MLX5_GLUE, RTLD_LAZY);
+       while (!handle && i != RTE_DIM(path)) {
+               const char *end;
+               size_t len;
+               int ret;
+
+               if (!path[i]) {
+                       ++i;
+                       continue;
+               }
+               end = strpbrk(path[i], ":;");
+               if (!end)
+                       end = path[i] + strlen(path[i]);
+               len = end - path[i];
+               ret = 0;
+               do {
+                       char name[ret + 1];
+
+                       ret = snprintf(name, sizeof(name), "%.*s%s" MLX5_GLUE,
+                                      (int)len, path[i],
+                                      (!len || *(end - 1) == '/') ? "" : "/");
+                       if (ret == -1)
+                               break;
+                       if (sizeof(name) != (size_t)ret + 1)
+                               continue;
+                       DEBUG("looking for rdma-core glue as \"%s\"", name);
+                       handle = dlopen(name, RTLD_LAZY);
+                       break;
+               } while (1);
+               path[i] = end + 1;
+               if (!*end)
+                       ++i;
+       }
        if (!handle) {
                rte_errno = EINVAL;
                dlmsg = dlerror();