lmkd: Introduce liblmkd_utils for communicating with lmkd process

(cherry pick from commit 0f1005180513e880bf7c90a3f2c2bf1a36aa1406)

A number of tools and tests require communication with lmkd.
In order to avoid code duplication liblmkd_utils implements
functions commonly used when interacting with lmkd process.
Isolate communication protocol details into lmkd.h

Bug: 63631020

Change-Id: Id840983d55b7db60013d52dee0c3187943811822
Merged-In: Id840983d55b7db60013d52dee0c3187943811822
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

Android.bp

@@ -6,6 +6,7 @@ cc_binary {
         "liblog",
         "libcutils",
     ],
+    local_include_dirs: ["include"],
     cflags: ["-Werror"],
 
     init_rc: ["lmkd.rc"],
@@ -18,3 +19,17 @@ cc_binary {
         },
     },
 }
+
+cc_library_static {
+    name: "liblmkd_utils",
+    srcs: ["liblmkd_utils.c"],
+    shared_libs: [
+        "libcutils",
+    ],
+    export_include_dirs: ["include"],
+    cppflags: [
+        "-g",
+        "-Wall",
+        "-Werror",
+    ]
+}

include/liblmkd_utils.h

@@ -0,0 +1,54 @@
+/*
+ *  Copyright 2018 Google, Inc
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#ifndef _LIBLMKD_UTILS_H_
+#define _LIBLMKD_UTILS_H_
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+#include <lmkd.h>
+
+__BEGIN_DECLS
+
+/*
+ * Connects to lmkd process and returns socket handle.
+ * On success returns socket handle.
+ * On error, -1 is returned, and errno is set appropriately.
+ */
+int lmkd_connect();
+
+/*
+ * Registers a process with lmkd and sets its oomadj score.
+ * On success returns 0.
+ * On error, -1 is returned.
+ * In the case of error errno is set appropriately.
+ */
+int lmkd_register_proc(int sock, struct lmk_procprio *params);
+
+/*
+ * Creates memcg directory for given process.
+ * On success returns 0.
+ * -1 is returned if path creation failed.
+ * -2 is returned if tasks file open operation failed.
+ * -3 is returned if tasks file write operation failed.
+ * In the case of error errno is set appropriately.
+ */
+int create_memcg(uid_t uid, pid_t pid);
+
+__END_DECLS
+
+#endif /* _LIBLMKD_UTILS_H_ */

include/lmkd.h

@@ -0,0 +1,147 @@
+/*
+ *  Copyright 2018 Google, Inc
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#ifndef _LMKD_H_
+#define _LMKD_H_
+
+#include <arpa/inet.h>
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+__BEGIN_DECLS
+
+/*
+ * Supported LMKD commands
+ */
+enum lmk_cmd {
+    LMK_TARGET = 0,  /* Associate minfree with oom_adj_score */
+    LMK_PROCPRIO,    /* Register a process and set its oom_adj_score */
+    LMK_PROCREMOVE,  /* Unregister a process */
+};
+
+/*
+ * Max number of targets in LMK_TARGET command.
+ */
+#define MAX_TARGETS 6
+
+/*
+ * Max packet length in bytes.
+ * Longest packet is LMK_TARGET followed by MAX_TARGETS
+ * of minfree and oom_adj_score values
+ */
+#define CTRL_PACKET_MAX_SIZE (sizeof(int) * (MAX_TARGETS * 2 + 1))
+
+/* LMKD packet - first int is lmk_cmd followed by payload */
+typedef int LMKD_CTRL_PACKET[CTRL_PACKET_MAX_SIZE / sizeof(int)];
+
+/* Get LMKD packet command */
+inline enum lmk_cmd lmkd_pack_get_cmd(LMKD_CTRL_PACKET pack) {
+    return (enum lmk_cmd)ntohl(pack[0]);
+}
+
+/* LMK_TARGET packet payload */
+struct lmk_target {
+    int minfree;
+    int oom_adj_score;
+};
+
+/*
+ * For LMK_TARGET packet get target_idx-th payload.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline void lmkd_pack_get_target(LMKD_CTRL_PACKET packet,
+                                 int target_idx, struct lmk_target *target) {
+    target->minfree = ntohl(packet[target_idx * 2 + 1]);
+    target->oom_adj_score = ntohl(packet[target_idx * 2 + 2]);
+}
+
+/*
+ * Prepare LMK_TARGET packet and return packet size in bytes.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline size_t lmkd_pack_set_target(LMKD_CTRL_PACKET packet,
+                                   struct lmk_target *targets,
+                                   size_t target_cnt) {
+    int idx = 0;
+    packet[idx++] = htonl(LMK_TARGET);
+    while (target_cnt) {
+        packet[idx++] = htonl(targets->minfree);
+        packet[idx++] = htonl(targets->oom_adj_score);
+        targets++;
+        target_cnt--;
+    }
+    return idx * sizeof(int);
+}
+
+/* LMK_PROCPRIO packet payload */
+struct lmk_procprio {
+    pid_t pid;
+    uid_t uid;
+    int oomadj;
+};
+
+/*
+ * For LMK_PROCPRIO packet get its payload.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline void lmkd_pack_get_procprio(LMKD_CTRL_PACKET packet,
+                                   struct lmk_procprio *params) {
+    params->pid = (pid_t)ntohl(packet[1]);
+    params->uid = (uid_t)ntohl(packet[2]);
+    params->oomadj = ntohl(packet[3]);
+}
+
+/*
+ * Prepare LMK_PROCPRIO packet and return packet size in bytes.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline size_t lmkd_pack_set_procprio(LMKD_CTRL_PACKET packet,
+                                   struct lmk_procprio *params) {
+    packet[0] = htonl(LMK_PROCPRIO);
+    packet[1] = htonl(params->pid);
+    packet[2] = htonl(params->uid);
+    packet[3] = htonl(params->oomadj);
+    return 4 * sizeof(int);
+}
+
+/* LMK_PROCREMOVE packet payload */
+struct lmk_procremove {
+    pid_t pid;
+};
+
+/*
+ * For LMK_PROCREMOVE packet get its payload.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline void lmkd_pack_get_procremove(LMKD_CTRL_PACKET packet,
+                                   struct lmk_procremove *params) {
+    params->pid = (pid_t)ntohl(packet[1]);
+}
+
+/*
+ * Prepare LMK_PROCREMOVE packet and return packet size in bytes.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline size_t lmkd_pack_set_procremove(LMKD_CTRL_PACKET packet,
+                                   struct lmk_procprio *params) {
+    packet[0] = htonl(LMK_PROCREMOVE);
+    packet[1] = htonl(params->pid);
+    return 2 * sizeof(int);
+}
+
+__END_DECLS
+
+#endif /* _LMKD_H_ */

liblmkd_utils.c

@@ -0,0 +1,76 @@
+/*
+ *  Copyright 2018 Google, Inc
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/cdefs.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <liblmkd_utils.h>
+#include <cutils/sockets.h>
+
+int lmkd_connect() {
+    return socket_local_client("lmkd",
+                               ANDROID_SOCKET_NAMESPACE_RESERVED,
+                               SOCK_SEQPACKET);
+}
+
+int lmkd_register_proc(int sock, struct lmk_procprio *params) {
+    LMKD_CTRL_PACKET packet;
+    size_t size;
+    int ret;
+
+    size = lmkd_pack_set_procprio(packet, params);
+    ret = TEMP_FAILURE_RETRY(write(sock, packet, size));
+
+    return (ret < 0) ? -1 : 0;
+}
+
+int create_memcg(uid_t uid, pid_t pid) {
+    char buf[256];
+    int tasks_file;
+    int written;
+
+    snprintf(buf, sizeof(buf), "/dev/memcg/apps/uid_%u", uid);
+    if (mkdir(buf, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH) < 0 &&
+        errno != EEXIST) {
+        return -1;
+    }
+
+    snprintf(buf, sizeof(buf), "/dev/memcg/apps/uid_%u/pid_%u", uid, pid);
+    if (mkdir(buf, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH) < 0 &&
+        errno != EEXIST) {
+        return -1;
+    }
+
+    snprintf(buf, sizeof(buf), "/dev/memcg/apps/uid_%u/pid_%u/tasks", uid, pid);
+    tasks_file = open(buf, O_WRONLY);
+    if (tasks_file < 0) {
+        return -2;
+    }
+    written = snprintf(buf, sizeof(buf), "%u", pid);
+    if (__predict_false(written >= (int)sizeof(buf))) {
+        written = sizeof(buf) - 1;
+    }
+    written = TEMP_FAILURE_RETRY(write(tasks_file, buf, written));
+    close(tasks_file);
+
+    return (written < 0) ? -3 : 0;
+}
+

lmkd.c

@@ -16,7 +16,6 @@
 
 #define LOG_TAG "lowmemorykiller"
 
-#include <arpa/inet.h>
 #include <errno.h>
 #include <inttypes.h>
 #include <sched.h>
@@ -34,6 +33,7 @@
 
 #include <cutils/properties.h>
 #include <cutils/sockets.h>
+#include <lmkd.h>
 #include <log/log.h>
 
 /*
@@ -71,19 +71,6 @@
 #define ARRAY_SIZE(x)   (sizeof(x) / sizeof(*(x)))
 #define EIGHT_MEGA (1 << 23)
 
-enum lmk_cmd {
-    LMK_TARGET,
-    LMK_PROCPRIO,
-    LMK_PROCREMOVE,
-};
-
-#define MAX_TARGETS 6
-/*
- * longest is LMK_TARGET followed by MAX_TARGETS each minfree and minkillprio
- * values
- */
-#define CTRL_PACKET_MAX (sizeof(int) * (MAX_TARGETS * 2 + 1))
-
 /* default to old in-kernel interface if no memory pressure events */
 static int use_inkernel_interface = 1;
 static bool has_inkernel_module;
@@ -300,45 +287,49 @@ static void writefilestring(const char *path, char *s) {
     close(fd);
 }
 
-static void cmd_procprio(int pid, int uid, int oomadj) {
+static void cmd_procprio(LMKD_CTRL_PACKET packet) {
     struct proc *procp;
     char path[80];
     char val[20];
     int soft_limit_mult;
+    struct lmk_procprio params;
 
-    if (oomadj < OOM_SCORE_ADJ_MIN || oomadj > OOM_SCORE_ADJ_MAX) {
+    lmkd_pack_get_procprio(packet, &params);
-        ALOGE("Invalid PROCPRIO oomadj argument %d", oomadj);
+
+    if (params.oomadj < OOM_SCORE_ADJ_MIN ||
+        params.oomadj > OOM_SCORE_ADJ_MAX) {
+        ALOGE("Invalid PROCPRIO oomadj argument %d", params.oomadj);
         return;
     }
 
-    snprintf(path, sizeof(path), "/proc/%d/oom_score_adj", pid);
+    snprintf(path, sizeof(path), "/proc/%d/oom_score_adj", params.pid);
-    snprintf(val, sizeof(val), "%d", oomadj);
+    snprintf(val, sizeof(val), "%d", params.oomadj);
     writefilestring(path, val);
 
     if (use_inkernel_interface)
         return;
 
-    if (oomadj >= 900) {
+    if (params.oomadj >= 900) {
         soft_limit_mult = 0;
-    } else if (oomadj >= 800) {
+    } else if (params.oomadj >= 800) {
         soft_limit_mult = 0;
-    } else if (oomadj >= 700) {
+    } else if (params.oomadj >= 700) {
         soft_limit_mult = 0;
-    } else if (oomadj >= 600) {
+    } else if (params.oomadj >= 600) {
         // Launcher should be perceptible, don't kill it.
-        oomadj = 200;
+        params.oomadj = 200;
         soft_limit_mult = 1;
-    } else if (oomadj >= 500) {
+    } else if (params.oomadj >= 500) {
         soft_limit_mult = 0;
-    } else if (oomadj >= 400) {
+    } else if (params.oomadj >= 400) {
         soft_limit_mult = 0;
-    } else if (oomadj >= 300) {
+    } else if (params.oomadj >= 300) {
         soft_limit_mult = 1;
-    } else if (oomadj >= 200) {
+    } else if (params.oomadj >= 200) {
         soft_limit_mult = 2;
-    } else if (oomadj >= 100) {
+    } else if (params.oomadj >= 100) {
         soft_limit_mult = 10;
-    } else if (oomadj >=   0) {
+    } else if (params.oomadj >=   0) {
         soft_limit_mult = 20;
     } else {
         // Persistent processes will have a large
@@ -346,11 +337,13 @@ static void cmd_procprio(int pid, int uid, int oomadj) {
         soft_limit_mult = 64;
     }
 
-    snprintf(path, sizeof(path), "/dev/memcg/apps/uid_%d/pid_%d/memory.soft_limit_in_bytes", uid, pid);
+    snprintf(path, sizeof(path),
+             "/dev/memcg/apps/uid_%d/pid_%d/memory.soft_limit_in_bytes",
+             params.uid, params.pid);
     snprintf(val, sizeof(val), "%d", soft_limit_mult * EIGHT_MEGA);
     writefilestring(path, val);
 
-    procp = pid_lookup(pid);
+    procp = pid_lookup(params.pid);
     if (!procp) {
             procp = malloc(sizeof(struct proc));
             if (!procp) {
@@ -358,33 +351,38 @@ static void cmd_procprio(int pid, int uid, int oomadj) {
                 return;
             }
 
-            procp->pid = pid;
+            procp->pid = params.pid;
-            procp->uid = uid;
+            procp->uid = params.uid;
-            procp->oomadj = oomadj;
+            procp->oomadj = params.oomadj;
             proc_insert(procp);
     } else {
         proc_unslot(procp);
-        procp->oomadj = oomadj;
+        procp->oomadj = params.oomadj;
         proc_slot(procp);
     }
 }
 
-static void cmd_procremove(int pid) {
+static void cmd_procremove(LMKD_CTRL_PACKET packet) {
+    struct lmk_procremove params;
+
     if (use_inkernel_interface)
         return;
 
-    pid_remove(pid);
+    lmkd_pack_get_procremove(packet, &params);
+    pid_remove(params.pid);
 }
 
-static void cmd_target(int ntargets, int *params) {
+static void cmd_target(int ntargets, LMKD_CTRL_PACKET packet) {
     int i;
+    struct lmk_target target;
 
     if (ntargets > (int)ARRAY_SIZE(lowmem_adj))
         return;
 
     for (i = 0; i < ntargets; i++) {
-        lowmem_minfree[i] = ntohl(*params++);
+        lmkd_pack_get_target(packet, i, &target);
-        lowmem_adj[i] = ntohl(*params++);
+        lowmem_minfree[i] = target.minfree;
+        lowmem_adj[i] = target.oom_adj_score;
     }
 
     lowmem_targets_size = ntargets;
@@ -445,38 +443,42 @@ static int ctrl_data_read(int dsock_idx, char *buf, size_t bufsz) {
 }
 
 static void ctrl_command_handler(int dsock_idx) {
-    int ibuf[CTRL_PACKET_MAX / sizeof(int)];
+    LMKD_CTRL_PACKET packet;
     int len;
-    int cmd = -1;
+    enum lmk_cmd cmd;
     int nargs;
     int targets;
 
-    len = ctrl_data_read(dsock_idx, (char *)ibuf, CTRL_PACKET_MAX);
+    len = ctrl_data_read(dsock_idx, (char *)packet, CTRL_PACKET_MAX_SIZE);
     if (len <= 0)
         return;
 
+    if (len < (int)sizeof(int)) {
+        ALOGE("Wrong control socket read length len=%d", len);
+        return;
+    }
+
+    cmd = lmkd_pack_get_cmd(packet);
     nargs = len / sizeof(int) - 1;
     if (nargs < 0)
         goto wronglen;
 
-    cmd = ntohl(ibuf[0]);
-
     switch(cmd) {
     case LMK_TARGET:
         targets = nargs / 2;
         if (nargs & 0x1 || targets > (int)ARRAY_SIZE(lowmem_adj))
             goto wronglen;
-        cmd_target(targets, &ibuf[1]);
+        cmd_target(targets, packet);
         break;
     case LMK_PROCPRIO:
         if (nargs != 3)
             goto wronglen;
-        cmd_procprio(ntohl(ibuf[1]), ntohl(ibuf[2]), ntohl(ibuf[3]));
+        cmd_procprio(packet);
         break;
     case LMK_PROCREMOVE:
         if (nargs != 1)
             goto wronglen;
-        cmd_procremove(ntohl(ibuf[1]));
+        cmd_procremove(packet);
         break;
     default:
         ALOGE("Received unknown command code %d", cmd);