4 files changed, 59 insertions, 13 deletions

diff --git a/src/sss_client/nss_mc.h b/src/sss_client/nss_mc.h
index f3abaab9c..839a930e2 100644
--- a/src/sss_client/nss_mc.h
+++ b/src/sss_client/nss_mc.h
@@ -33,9 +33,15 @@
 typedef int errno_t;
 #endif
 
+enum sss_mc_state {
+    UNINITIALIZED = 0,
+    INITIALIZED,
+    RECYCLED,
+};
+
 /* common stuff */
 struct sss_cli_mc_ctx {
-    bool initialized;
+    enum sss_mc_state initialized;
     int fd;
 
     uint32_t seed;          /* seed from the tables header */
@@ -48,6 +54,8 @@ struct sss_cli_mc_ctx {
 
     uint32_t *hash_table;   /* hash table address (in mmap) */
     uint32_t ht_size;       /* size of hash table */
+
+    uint32_t active_threads; /* count of threads which use memory cache */
 };
 
 errno_t sss_nss_mc_get_ctx(const char *name, struct sss_cli_mc_ctx *ctx);
diff --git a/src/sss_client/nss_mc_common.c b/src/sss_client/nss_mc_common.c
index 7845f8389..bb776fb11 100644
--- a/src/sss_client/nss_mc_common.c
+++ b/src/sss_client/nss_mc_common.c
@@ -123,7 +123,7 @@ static errno_t sss_nss_mc_init_ctx(const char *name,
 
     sss_nss_lock();
     /* check if ctx is initialised by previous thread. */
-    if (ctx->initialized) {
+    if (ctx->initialized != UNINITIALIZED) {
         ret = sss_nss_check_header(ctx);
         goto done;
     }
@@ -163,7 +163,7 @@ static errno_t sss_nss_mc_init_ctx(const char *name,
         goto done;
     }
 
-    ctx->initialized = true;
+    ctx->initialized = INITIALIZED;
 
     ret = 0;
 
@@ -181,22 +181,52 @@ errno_t sss_nss_mc_get_ctx(const char *name, struct sss_cli_mc_ctx *ctx)
 {
     char *envval;
     int ret;
+    bool need_decrement = false;
 
     envval = getenv("SSS_NSS_USE_MEMCACHE");
     if (envval && strcasecmp(envval, "NO") == 0) {
         return EPERM;
     }
 
-    if (ctx->initialized) {
+    switch (ctx->initialized) {
+    case UNINITIALIZED:
+        __sync_add_and_fetch(&ctx->active_threads, 1);
+        ret = sss_nss_mc_init_ctx(name, ctx);
+        if (ret) {
+            need_decrement = true;
+        }
+        break;
+    case INITIALIZED:
+        __sync_add_and_fetch(&ctx->active_threads, 1);
         ret = sss_nss_check_header(ctx);
-        goto done;
+        if (ret) {
+            need_decrement = true;
+        }
+        break;
+    case RECYCLED:
+        /* we need to safely destroy memory cache */
+        ret = EAGAIN;
+        break;
+    default:
+        ret = EFAULT;
     }
 
-    ret = sss_nss_mc_init_ctx(name, ctx);
-
-done:
     if (ret) {
-        sss_nss_mc_destroy_ctx(ctx);
+        if (ctx->initialized == INITIALIZED) {
+            ctx->initialized = RECYCLED;
+        }
+        if (ctx->initialized == RECYCLED && ctx->active_threads == 0) {
+            /* just one thread should call munmap */
+            sss_nss_lock();
+            if (ctx->initialized == RECYCLED) {
+                sss_nss_mc_destroy_ctx(ctx);
+            }
+            sss_nss_unlock();
+        }
+        if (need_decrement) {
+            /* In case of error, we will not touch mmapped area => decrement */
+            __sync_sub_and_fetch(&ctx->active_threads, 1);
+        }
     }
     return ret;
 }
diff --git a/src/sss_client/nss_mc_group.c b/src/sss_client/nss_mc_group.c
index 8bb6f33ee..416f64b20 100644
--- a/src/sss_client/nss_mc_group.c
+++ b/src/sss_client/nss_mc_group.c
@@ -28,7 +28,8 @@
 #include <time.h>
 #include "nss_mc.h"
 
-struct sss_cli_mc_ctx gr_mc_ctx = { false, -1, 0, NULL, 0, NULL, 0, NULL, 0 };
+struct sss_cli_mc_ctx gr_mc_ctx = { UNINITIALIZED, -1, 0, NULL, 0, NULL, 0,
+                                    NULL, 0, 0 };
 
 static errno_t sss_nss_mc_parse_result(struct sss_mc_rec *rec,
                                        struct group *result,
@@ -168,6 +169,7 @@ errno_t sss_nss_mc_getgrnam(const char *name, size_t name_len,
 
 done:
     free(rec);
+    __sync_sub_and_fetch(&gr_mc_ctx.active_threads, 1);
     return ret;
 }
 
@@ -190,7 +192,8 @@ errno_t sss_nss_mc_getgrgid(gid_t gid,
 
     len = snprintf(gidstr, 11, "%ld", (long)gid);
     if (len > 10) {
-        return EINVAL;
+        ret = EINVAL;
+        goto done;
     }
 
     /* hashes are calculated including the NULL terminator */
@@ -234,6 +237,7 @@ errno_t sss_nss_mc_getgrgid(gid_t gid,
 
 done:
     free(rec);
+    __sync_sub_and_fetch(&gr_mc_ctx.active_threads, 1);
     return ret;
 }
 
diff --git a/src/sss_client/nss_mc_passwd.c b/src/sss_client/nss_mc_passwd.c
index b952b3658..bbc07a870 100644
--- a/src/sss_client/nss_mc_passwd.c
+++ b/src/sss_client/nss_mc_passwd.c
@@ -28,7 +28,8 @@
 #include <time.h>
 #include "nss_mc.h"
 
-struct sss_cli_mc_ctx pw_mc_ctx = { false, -1, 0, NULL, 0, NULL, 0, NULL, 0 };
+struct sss_cli_mc_ctx pw_mc_ctx = { UNINITIALIZED, -1, 0, NULL, 0, NULL, 0,
+                                    NULL, 0, 0 };
 
 static errno_t sss_nss_mc_parse_result(struct sss_mc_rec *rec,
                                        struct passwd *result,
@@ -170,6 +171,7 @@ errno_t sss_nss_mc_getpwnam(const char *name, size_t name_len,
 
 done:
     free(rec);
+    __sync_sub_and_fetch(&pw_mc_ctx.active_threads, 1);
     return ret;
 }
 
@@ -192,7 +194,8 @@ errno_t sss_nss_mc_getpwuid(uid_t uid,
 
     len = snprintf(uidstr, 11, "%ld", (long)uid);
     if (len > 10) {
-        return EINVAL;
+        ret = EINVAL;
+        goto done;
     }
 
     /* hashes are calculated including the NULL terminator */
@@ -236,6 +239,7 @@ errno_t sss_nss_mc_getpwuid(uid_t uid,
 
 done:
     free(rec);
+    __sync_sub_and_fetch(&pw_mc_ctx.active_threads, 1);
     return ret;
 }