core: avoid dynamic TLS allocation when possible

Some interdependencies between logging and memory management functions
make it impossible to use the logging framework before initializing
memory subsystem because they both depend on Thread Local Storage
allocated through pthread_key_create() during initialization.

This causes a crash when we try to log something very early in the
initialization phase.

To prevent this, several dynamically allocated TLS structures have
been replaced by static TLS reserved at compile time using '__thread'
keyword. This also reduces the number of error sources, making
initialization simpler.

Backport of:
> BUG: 1193929
> Change-Id: I8ea2e072411e30790d50084b6b7e909c7bb01d50
> Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

Updates: bz#1724210
Change-Id: I8ea2e072411e30790d50084b6b7e909c7bb01d50
Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

1 files changed, 19 insertions, 114 deletions

diff --git a/libglusterfs/src/syncop.c b/libglusterfs/src/syncop.c
index c05939a7915..2eb7b49fc4c 100644
--- a/libglusterfs/src/syncop.c
+++ b/libglusterfs/src/syncop.c
@@ -26,28 +26,10 @@ syncopctx_setfsuid(void *uid)
 
     opctx = syncopctx_getctx();
 
-    /* alloc for this thread the first time */
-    if (!opctx) {
-        opctx = GF_CALLOC(1, sizeof(*opctx), gf_common_mt_syncopctx);
-        if (!opctx) {
-            ret = -1;
-            goto out;
-        }
-
-        ret = syncopctx_setctx(opctx);
-        if (ret != 0) {
-            GF_FREE(opctx);
-            opctx = NULL;
-            goto out;
-        }
-    }
+    opctx->uid = *(uid_t *)uid;
+    opctx->valid |= SYNCOPCTX_UID;
 
 out:
-    if (opctx && uid) {
-        opctx->uid = *(uid_t *)uid;
-        opctx->valid |= SYNCOPCTX_UID;
-    }
-
     return ret;
 }
 
@@ -66,28 +48,10 @@ syncopctx_setfsgid(void *gid)
 
     opctx = syncopctx_getctx();
 
-    /* alloc for this thread the first time */
-    if (!opctx) {
-        opctx = GF_CALLOC(1, sizeof(*opctx), gf_common_mt_syncopctx);
-        if (!opctx) {
-            ret = -1;
-            goto out;
-        }
-
-        ret = syncopctx_setctx(opctx);
-        if (ret != 0) {
-            GF_FREE(opctx);
-            opctx = NULL;
-            goto out;
-        }
-    }
+    opctx->gid = *(gid_t *)gid;
+    opctx->valid |= SYNCOPCTX_GID;
 
 out:
-    if (opctx && gid) {
-        opctx->gid = *(gid_t *)gid;
-        opctx->valid |= SYNCOPCTX_GID;
-    }
-
     return ret;
 }
 
@@ -107,43 +71,20 @@ syncopctx_setfsgroups(int count, const void *groups)
 
     opctx = syncopctx_getctx();
 
-    /* alloc for this thread the first time */
-    if (!opctx) {
-        opctx = GF_CALLOC(1, sizeof(*opctx), gf_common_mt_syncopctx);
-        if (!opctx) {
-            ret = -1;
-            goto out;
-        }
-
-        ret = syncopctx_setctx(opctx);
-        if (ret != 0) {
-            GF_FREE(opctx);
-            opctx = NULL;
-            goto out;
-        }
-    }
-
     /* resize internal groups as required */
     if (count && opctx->grpsize < count) {
         if (opctx->groups) {
-            tmpgroups = GF_REALLOC(opctx->groups, (sizeof(gid_t) * count));
-            /* NOTE: Not really required to zero the reallocation,
-             * as ngrps controls the validity of data,
-             * making a note irrespective */
-            if (tmpgroups == NULL) {
-                opctx->grpsize = 0;
-                GF_FREE(opctx->groups);
-                opctx->groups = NULL;
-                ret = -1;
-                goto out;
-            }
-        } else {
-            tmpgroups = GF_CALLOC(count, sizeof(gid_t), gf_common_mt_syncopctx);
-            if (tmpgroups == NULL) {
-                opctx->grpsize = 0;
-                ret = -1;
-                goto out;
-            }
+            /* Group list will be updated later, so no need to keep current
+             * data and waste time copying it. It's better to free the current
+             * allocation and then allocate a fresh new memory block. */
+            GF_FREE(opctx->groups);
+            opctx->groups = NULL;
+            opctx->grpsize = 0;
+        }
+        tmpgroups = GF_MALLOC(count * sizeof(gid_t), gf_common_mt_syncopctx);
+        if (tmpgroups == NULL) {
+            ret = -1;
+            goto out;
         }
 
         opctx->groups = tmpgroups;
@@ -177,28 +118,10 @@ syncopctx_setfspid(void *pid)
 
     opctx = syncopctx_getctx();
 
-    /* alloc for this thread the first time */
-    if (!opctx) {
-        opctx = GF_CALLOC(1, sizeof(*opctx), gf_common_mt_syncopctx);
-        if (!opctx) {
-            ret = -1;
-            goto out;
-        }
-
-        ret = syncopctx_setctx(opctx);
-        if (ret != 0) {
-            GF_FREE(opctx);
-            opctx = NULL;
-            goto out;
-        }
-    }
+    opctx->pid = *(pid_t *)pid;
+    opctx->valid |= SYNCOPCTX_PID;
 
 out:
-    if (opctx && pid) {
-        opctx->pid = *(pid_t *)pid;
-        opctx->valid |= SYNCOPCTX_PID;
-    }
-
     return ret;
 }
 
@@ -217,28 +140,10 @@ syncopctx_setfslkowner(gf_lkowner_t *lk_owner)
 
     opctx = syncopctx_getctx();
 
-    /* alloc for this thread the first time */
-    if (!opctx) {
-        opctx = GF_CALLOC(1, sizeof(*opctx), gf_common_mt_syncopctx);
-        if (!opctx) {
-            ret = -1;
-            goto out;
-        }
-
-        ret = syncopctx_setctx(opctx);
-        if (ret != 0) {
-            GF_FREE(opctx);
-            opctx = NULL;
-            goto out;
-        }
-    }
+    opctx->lk_owner = *lk_owner;
+    opctx->valid |= SYNCOPCTX_LKOWNER;
 
 out:
-    if (opctx && lk_owner) {
-        opctx->lk_owner = *lk_owner;
-        opctx->valid |= SYNCOPCTX_LKOWNER;
-    }
-
     return ret;
 }