Skip to content

kernel_liteos_a_note
kernel_liteos_a_note

qq_41844952 / kernel_liteos_a_note
与 Fork 源项目一致

Fork自 鸿蒙内核源码分析 / 注释鸿蒙内核源码

通知 1
Star 0
Fork 0
kernel_liteos_a_note
kernel_liteos_a_note

前往新版Gitcode，体验更适合开发者的 AI 搜索 >>

提交 2f73237a 编写于 作者: 鸿蒙内核源码分析's avatar 鸿蒙内核源码分析
浏览文件
操作

鸿蒙源码分析系列篇 https://blog.csdn.net/kuangyufei https://my.oschina.net/u/3751245

上级 4e89c02a
隐藏空白更改
内联 并排
Showing with 102 addition and 88 deletion
arch/arm/arm/src/user_copy.c
浏览文件 @ 2f73237a
...@@ -61,7 +61,7 @@ size_t arch_copy_to_user(void *dst, const void *src, size_t len) ...@@ -61,7 +61,7 @@ size_t arch_copy_to_user(void *dst, const void *src, size_t len)
} }
size_t LOS_ArchCopyToUser(void *dst, const void *src, size_t len) size_t LOS_ArchCopyToUser(void *dst, const void *src, size_t len)
{ {//先判断地址是不是在用户空间
if (!LOS_IsUserAddressRange((VADDR_T)(UINTPTR)dst, len)) { if (!LOS_IsUserAddressRange((VADDR_T)(UINTPTR)dst, len)) {
return len; return len;
} }
......
kernel/base/include/los_vm_filemap.h
浏览文件 @ 2f73237a
...@@ -168,14 +168,14 @@ STATIC INLINE BOOL OsIsPageMapped(LosFilePage *page) ...@@ -168,14 +168,14 @@ STATIC INLINE BOOL OsIsPageMapped(LosFilePage *page)
/* The follow three functions is used to SHM module */ /* The follow three functions is used to SHM module */
STATIC INLINE VOID OsSetPageShared(LosVmPage *page) STATIC INLINE VOID OsSetPageShared(LosVmPage *page)
{ {
LOS_BitmapSet(&page->flags, FILE_PAGE_SHARED); LOS_BitmapSet(&page->flags, FILE_PAGE_SHARED);//设为共享页面,共享页位 置0
} }
//取消共享页属性
STATIC INLINE VOID OsCleanPageShared(LosVmPage *page) STATIC INLINE VOID OsCleanPageShared(LosVmPage *page)
{ {
LOS_BitmapClr(&page->flags, FILE_PAGE_SHARED); LOS_BitmapClr(&page->flags, FILE_PAGE_SHARED);//共享页位 置0
} }
//是否为共享页
STATIC INLINE BOOL OsIsPageShared(LosVmPage *page) STATIC INLINE BOOL OsIsPageShared(LosVmPage *page)
{ {
return BIT_GET(page->flags, FILE_PAGE_SHARED); return BIT_GET(page->flags, FILE_PAGE_SHARED);
......
kernel/base/vm/los_vm_map.c
浏览文件 @ 2f73237a
...@@ -453,7 +453,7 @@ LosVmMapRegion *OsCreateRegion(VADDR_T vaddr, size_t len, UINT32 regionFlags, un ...@@ -453,7 +453,7 @@ LosVmMapRegion *OsCreateRegion(VADDR_T vaddr, size_t len, UINT32 regionFlags, un
region->regionFlags = regionFlags;//标识,可读可写可执行这些 region->regionFlags = regionFlags;//标识,可读可写可执行这些
region->regionType = VM_MAP_REGION_TYPE_NONE;//未映射 region->regionType = VM_MAP_REGION_TYPE_NONE;//未映射
region->forkFlags = 0;// region->forkFlags = 0;//
region->shmid = -1; region->shmid = -1; //默认线性区为不共享,无共享资源ID
return region; return region;
} }
//通过虚拟地址查询物理地址 //通过虚拟地址查询物理地址
......
kernel/base/vm/shm.c
浏览文件 @ 2f73237a
...@@ -73,31 +73,31 @@ STATIC LosMux g_sysvShmMux; ...@@ -73,31 +73,31 @@ STATIC LosMux g_sysvShmMux;
#define SHM_M 010000 #define SHM_M 010000
#endif #endif
#ifndef ACCESSPERMS #ifndef ACCESSPERMS //出工程区了,详见..\vendor_hisi_hi3861_hi3861\hi3861\platform\os\Huawei_LiteOS\components\lib\libc\musl\include\sys\stat.h
#define ACCESSPERMS (S_IRWXU | S_IRWXG | S_IRWXO) #define ACCESSPERMS (S_IRWXU | S_IRWXG | S_IRWXO)//文件权限值意思就是 用户,用户组,其他可读可写.
#endif #endif //代表含义U:user G:group O:other
#define SHM_GROUPE_TO_USER 3 #define SHM_GROUPE_TO_USER 3
#define SHM_OTHER_TO_USER 6 #define SHM_OTHER_TO_USER 6
/* private structure */ /* private structure */
struct shmSegMap { struct shmSegMap {
vaddr_t vaddr; vaddr_t vaddr; //虚拟地址
INT32 shmID; INT32 shmID; //可看出共享内存使用了ID管理机制
}; };
//结构体定义可见于..\vendor_hisi_hi3861_hi3861\hi3861\platform\os\Huawei_LiteOS\components\lib\libc\musl\arch\generic\bits\shm.h //结构体定义可见于..\vendor_hisi_hi3861_hi3861\hi3861\platform\os\Huawei_LiteOS\components\lib\libc\musl\arch\generic\bits\shm.h
struct shmIDSource { struct shmIDSource {//共享存储结构体
struct shmid_ds ds; struct shmid_ds ds; //是内核为每一个共享内存段维护的数据结构,包含权限,各进程最后操作的时间,进程ID等信息
UINT32 status; UINT32 status; //状态 SHM_SEG_FREE ...
LOS_DL_LIST node; LOS_DL_LIST node; //节点,挂vmPage
}; };
/* private data */ /* private data */
STATIC struct shminfo g_shmInfo = { STATIC struct shminfo g_shmInfo = {
.shmmax = SHM_MAX,//最大的内存segment的大小 .shmmax = SHM_MAX,//最大的内存segment的大小 50M
.shmmin = SHM_MIN,//最小的内存segment的大小 .shmmin = SHM_MIN,//最小的内存segment的大小 1M
.shmmni = SHM_MNI,//整个系统的内存segment的总个数 .shmmni = SHM_MNI,//整个系统的内存segment的总个数 :默认192 ShmAllocSeg
.shmseg = SHM_SEG,//每个进程可以使用的内存segment的最大个数 .shmseg = SHM_SEG,//每个进程可以使用的内存segment的最大个数 128
.shmall = SHM_ALL, .shmall = SHM_ALL,
}; };
...@@ -113,38 +113,38 @@ INT32 ShmInit(VOID) ...@@ -113,38 +113,38 @@ INT32 ShmInit(VOID)
return -1; return -1;
} }
g_shmSegs = LOS_MemAlloc((VOID *)OS_SYS_MEM_ADDR, sizeof(struct shmIDSource) * g_shmInfo.shmmni); g_shmSegs = LOS_MemAlloc((VOID *)OS_SYS_MEM_ADDR, sizeof(struct shmIDSource) * g_shmInfo.shmmni);//分配shm段数组
if (g_shmSegs == NULL) { if (g_shmSegs == NULL) {
(VOID)LOS_MuxDestroy(&g_sysvShmMux); (VOID)LOS_MuxDestroy(&g_sysvShmMux);
return -1; return -1;
} }
(VOID)memset_s(g_shmSegs, (sizeof(struct shmIDSource) * g_shmInfo.shmmni), (VOID)memset_s(g_shmSegs, (sizeof(struct shmIDSource) * g_shmInfo.shmmni),
0, (sizeof(struct shmIDSource) * g_shmInfo.shmmni)); 0, (sizeof(struct shmIDSource) * g_shmInfo.shmmni));//数组清零
for (i = 0; i < g_shmInfo.shmmni; i++) { for (i = 0; i < g_shmInfo.shmmni; i++) {
g_shmSegs[i].status = SHM_SEG_FREE; g_shmSegs[i].status = SHM_SEG_FREE;//节点初始状态为空闲
g_shmSegs[i].ds.shm_perm.seq = i + 1; g_shmSegs[i].ds.shm_perm.seq = i + 1;//struct ipc_perm shm_perm;系统为每一个IPC对象保存一个ipc_perm结构体,结构说明了IPC对象的权限和所有者
LOS_ListInit(&g_shmSegs[i].node); LOS_ListInit(&g_shmSegs[i].node);//初始化节点
} }
return 0; return 0;
} }
//共享内存释放初始化
INT32 ShmDeinit(VOID) INT32 ShmDeinit(VOID)
{ {
UINT32 ret; UINT32 ret;
(VOID)LOS_MemFree((VOID *)OS_SYS_MEM_ADDR, g_shmSegs); (VOID)LOS_MemFree((VOID *)OS_SYS_MEM_ADDR, g_shmSegs);//归还内存池
g_shmSegs = NULL; g_shmSegs = NULL;
ret = LOS_MuxDestroy(&g_sysvShmMux); ret = LOS_MuxDestroy(&g_sysvShmMux);//销毁互斥量
if (ret != LOS_OK) { if (ret != LOS_OK) {
return -1; return -1;
} }
return 0; return 0;
} }
//设置共享flag
STATIC inline VOID ShmSetSharedFlag(struct shmIDSource *seg) STATIC inline VOID ShmSetSharedFlag(struct shmIDSource *seg)
{ {
LosVmPage *page = NULL; LosVmPage *page = NULL;
...@@ -162,7 +162,7 @@ STATIC inline VOID ShmClearSharedFlag(struct shmIDSource *seg) ...@@ -162,7 +162,7 @@ STATIC inline VOID ShmClearSharedFlag(struct shmIDSource *seg)
OsCleanPageShared(page); OsCleanPageShared(page);
} }
} }
//seg下所有共享页引用减少
STATIC VOID ShmPagesRefDec(struct shmIDSource *seg) STATIC VOID ShmPagesRefDec(struct shmIDSource *seg)
{ {
LosVmPage *page = NULL; LosVmPage *page = NULL;
...@@ -171,7 +171,7 @@ STATIC VOID ShmPagesRefDec(struct shmIDSource *seg) ...@@ -171,7 +171,7 @@ STATIC VOID ShmPagesRefDec(struct shmIDSource *seg)
LOS_AtomicDec(&page->refCounts); LOS_AtomicDec(&page->refCounts);
} }
} }
//分配共享页
STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg) STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg)
{ {
INT32 i; INT32 i;
...@@ -186,9 +186,9 @@ STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg) ...@@ -186,9 +186,9 @@ STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg)
size = LOS_Align(size, PAGE_SIZE); size = LOS_Align(size, PAGE_SIZE);
for (i = 0; i < g_shmInfo.shmmni; i++) { for (i = 0; i < g_shmInfo.shmmni; i++) {
if (g_shmSegs[i].status & SHM_SEG_FREE) { if (g_shmSegs[i].status & SHM_SEG_FREE) {//找到空闲段
g_shmSegs[i].status &= ~SHM_SEG_FREE; g_shmSegs[i].status &= ~SHM_SEG_FREE;//变成非空闲状态
segNum = i; segNum = i;//标号
break; break;
} }
} }
...@@ -198,15 +198,15 @@ STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg) ...@@ -198,15 +198,15 @@ STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg)
} }
seg = &g_shmSegs[segNum]; seg = &g_shmSegs[segNum];
count = LOS_PhysPagesAlloc(size >> PAGE_SHIFT, &seg->node); count = LOS_PhysPagesAlloc(size >> PAGE_SHIFT, &seg->node);//分配共享页面,函数内部把node都挂好了.
if (count != (size >> PAGE_SHIFT)) { if (count != (size >> PAGE_SHIFT)) {//异常释放
(VOID)LOS_PhysPagesFree(&seg->node); (VOID)LOS_PhysPagesFree(&seg->node);//
seg->status = SHM_SEG_FREE; seg->status = SHM_SEG_FREE;//回归seg池
return -ENOMEM; return -ENOMEM;
} }
ShmSetSharedFlag(seg); ShmSetSharedFlag(seg);//node的每个页面设置为此乃共享页也
seg->status |= SHM_SEG_USED; seg->status |= SHM_SEG_USED; //段已使用
seg->ds.shm_perm.mode = (unsigned int)shmflg & ACCESSPERMS; seg->ds.shm_perm.mode = (unsigned int)shmflg & ACCESSPERMS;
seg->ds.shm_perm.key = key; seg->ds.shm_perm.key = key;
seg->ds.shm_segsz = size; seg->ds.shm_segsz = size;
...@@ -270,7 +270,7 @@ STATIC INT32 ShmSegValidCheck(INT32 segNum, size_t size, int shmFalg) ...@@ -270,7 +270,7 @@ STATIC INT32 ShmSegValidCheck(INT32 segNum, size_t size, int shmFalg)
return segNum; return segNum;
} }
//通过ID找到资源
STATIC struct shmIDSource *ShmFindSeg(int shmid) STATIC struct shmIDSource *ShmFindSeg(int shmid)
{ {
struct shmIDSource *seg = NULL; struct shmIDSource *seg = NULL;
...@@ -281,7 +281,7 @@ STATIC struct shmIDSource *ShmFindSeg(int shmid) ...@@ -281,7 +281,7 @@ STATIC struct shmIDSource *ShmFindSeg(int shmid)
} }
seg = &g_shmSegs[shmid]; seg = &g_shmSegs[shmid];
if ((seg->status & SHM_SEG_FREE) || (seg->status & SHM_SEG_REMOVE)) { if ((seg->status & SHM_SEG_FREE) || (seg->status & SHM_SEG_REMOVE)) {//空闲或删除时
set_errno(EIDRM); set_errno(EIDRM);
return NULL; return NULL;
} }
...@@ -306,13 +306,13 @@ STATIC VOID ShmVmmMapping(LosVmSpace *space, LOS_DL_LIST *pageList, VADDR_T vadd ...@@ -306,13 +306,13 @@ STATIC VOID ShmVmmMapping(LosVmSpace *space, LOS_DL_LIST *pageList, VADDR_T vadd
va += PAGE_SIZE; va += PAGE_SIZE;
} }
} }
//fork 一个共享线性区
VOID OsShmFork(LosVmSpace *space, LosVmMapRegion *oldRegion, LosVmMapRegion *newRegion) VOID OsShmFork(LosVmSpace *space, LosVmMapRegion *oldRegion, LosVmMapRegion *newRegion)
{ {
struct shmIDSource *seg = NULL; struct shmIDSource *seg = NULL;
SYSV_SHM_LOCK(); SYSV_SHM_LOCK();
seg = ShmFindSeg(oldRegion->shmid); seg = ShmFindSeg(oldRegion->shmid);//通过老区ID获取对应的共享资源ID结构体
if (seg == NULL) { if (seg == NULL) {
SYSV_SHM_UNLOCK(); SYSV_SHM_UNLOCK();
VM_ERR("shm fork failed!"); VM_ERR("shm fork failed!");
...@@ -364,7 +364,7 @@ STATIC INT32 ShmSegUsedCount(VOID) ...@@ -364,7 +364,7 @@ STATIC INT32 ShmSegUsedCount(VOID)
} }
return count; return count;
} }
//共享内存权限检查
STATIC INT32 ShmPermCheck(struct shmIDSource *seg, mode_t mode) STATIC INT32 ShmPermCheck(struct shmIDSource *seg, mode_t mode)
{ {
INT32 uid = LOS_GetUserID(); INT32 uid = LOS_GetUserID();
...@@ -405,9 +405,15 @@ STATIC INT32 ShmPermCheck(struct shmIDSource *seg, mode_t mode) ...@@ -405,9 +405,15 @@ STATIC INT32 ShmPermCheck(struct shmIDSource *seg, mode_t mode)
} }
/* /*
得到一个共享内存标识符或创建一个共享内存对象 得到一个共享内存标识符或创建一个共享内存对象
key_t:建立新共享内存对象 key_t: 建立新共享内存对象 标识符是IPC对象的内部名。为使多个合作进程能够在同一IPC对象上汇聚，需要提供一个外部命名方案。
为此，每个IPC对象都与一个键（key）相关联，这个键作为该对象的外部名,无论何时创建IPC结构（通过msgget、semget、shmget创建），
都应给IPC指定一个键, key_t由ftok创建,ftok当然在本工程里找不到,所以要写这么多.
size: 新建的共享内存大小，以字节为单位 size: 新建的共享内存大小，以字节为单位
shmflg: IPC_CREAT IPC_EXCL shmflg: IPC_CREAT IPC_EXCL
IPC_CREAT： 在创建新的IPC时，如果key参数是IPC_PRIVATE或者和当前某种类型的IPC结构无关，则需要指明flag参数的IPC_CREAT标志位，
则用来创建一个新的IPC结构。（如果IPC结构已存在，并且指定了IPC_CREAT，则IPC_CREAT什么都不做，函数也不出错）
IPC_EXCL： 此参数一般与IPC_CREAT配合使用来创建一个新的IPC结构。如果创建的IPC结构已存在函数就出错返回，
返回EEXIST（这与open函数指定O_CREAT和O_EXCL标志原理相同）
*/ */
INT32 ShmGet(key_t key, size_t size, INT32 shmflg) INT32 ShmGet(key_t key, size_t size, INT32 shmflg)
{ {
...@@ -466,13 +472,13 @@ INT32 ShmatParamCheck(const void *shmaddr, int shmflg) ...@@ -466,13 +472,13 @@ INT32 ShmatParamCheck(const void *shmaddr, int shmflg)
} }
if ((shmaddr != NULL) && !IS_PAGE_ALIGNED(shmaddr) && if ((shmaddr != NULL) && !IS_PAGE_ALIGNED(shmaddr) &&
((shmflg & SHM_RND) == 0)) { ((shmflg & SHM_RND) == 0)) {//取整 SHM_RND
return EINVAL; return EINVAL;
} }
return 0; return 0;
} }
//共享
LosVmMapRegion *ShmatVmmAlloc(struct shmIDSource *seg, const VOID *shmaddr, LosVmMapRegion *ShmatVmmAlloc(struct shmIDSource *seg, const VOID *shmaddr,
INT32 shmflg, UINT32 prot) INT32 shmflg, UINT32 prot)
{ {
...@@ -482,11 +488,11 @@ LosVmMapRegion *ShmatVmmAlloc(struct shmIDSource *seg, const VOID *shmaddr, ...@@ -482,11 +488,11 @@ LosVmMapRegion *ShmatVmmAlloc(struct shmIDSource *seg, const VOID *shmaddr,
UINT32 regionFlags; UINT32 regionFlags;
INT32 ret; INT32 ret;
regionFlags = OsCvtProtFlagsToRegionFlags(prot, MAP_ANONYMOUS | MAP_SHARED); regionFlags = OsCvtProtFlagsToRegionFlags(prot, MAP_ANONYMOUS | MAP_SHARED);//映射方式:共享或匿名
(VOID)LOS_MuxAcquire(&space->regionMux); (VOID)LOS_MuxAcquire(&space->regionMux);
if (shmaddr == NULL) { if (shmaddr == NULL) {//shm_segsz:段的大小（以字节为单位）
region = LOS_RegionAlloc(space, 0, seg->ds.shm_segsz, regionFlags, 0); region = LOS_RegionAlloc(space, 0, seg->ds.shm_segsz, regionFlags, 0);//分配一个区,注意这里的虚拟地址传的是0,
} else { } else {//如果地址虚拟地址传入是0，则由内核选择创建映射的虚拟地址， 这是创建新映射的最便捷的方法。
if (shmflg & SHM_RND) { if (shmflg & SHM_RND) {
vaddr = ROUNDDOWN((VADDR_T)(UINTPTR)shmaddr, SHMLBA); vaddr = ROUNDDOWN((VADDR_T)(UINTPTR)shmaddr, SHMLBA);
} else { } else {
...@@ -513,7 +519,11 @@ ERROR: ...@@ -513,7 +519,11 @@ ERROR:
(VOID)LOS_MuxRelease(&space->regionMux); (VOID)LOS_MuxRelease(&space->regionMux);
return NULL; return NULL;
} }
/* 共享存储的连接使用
一旦创建/引用了一个共享存储段，那么进程就可调用shmat函数将其连接到它的地址空间中
如果shmat成功执行，那么内核将使与该共享存储相关的shmid_ds结构中的shm_nattch计数器值加1
shmid 就是个索引,就跟进程和线程的ID一样 g_shmSegs[shmid] shmid > 192个
*/
VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg) VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg)
{ {
INT32 ret; INT32 ret;
...@@ -522,7 +532,7 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg) ...@@ -522,7 +532,7 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg)
LosVmMapRegion *r = NULL; LosVmMapRegion *r = NULL;
mode_t mode; mode_t mode;
ret = ShmatParamCheck(shmaddr, shmflg); ret = ShmatParamCheck(shmaddr, shmflg);//参数检查
if (ret != 0) { if (ret != 0) {
set_errno(ret); set_errno(ret);
return (VOID *)-1; return (VOID *)-1;
...@@ -535,19 +545,19 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg) ...@@ -535,19 +545,19 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg)
} }
SYSV_SHM_LOCK(); SYSV_SHM_LOCK();
seg = ShmFindSeg(shmid); seg = ShmFindSeg(shmid);//找到段
if (seg == NULL) { if (seg == NULL) {
SYSV_SHM_UNLOCK(); SYSV_SHM_UNLOCK();
return (VOID *)-1; return (VOID *)-1;
} }
mode = ((unsigned int)shmflg & SHM_RDONLY) ? SHM_R : (SHM_R | SHM_W); mode = ((unsigned int)shmflg & SHM_RDONLY) ? SHM_R : (SHM_R | SHM_W);//读写模式判断
ret = ShmPermCheck(seg, mode); ret = ShmPermCheck(seg, mode);
if (ret != 0) { if (ret != 0) {
goto ERROR; goto ERROR;
} }
seg->ds.shm_nattch++; seg->ds.shm_nattch++;//ds上记录有一个进程绑定上来
r = ShmatVmmAlloc(seg, shmaddr, shmflg, prot); r = ShmatVmmAlloc(seg, shmaddr, shmflg, prot);
if (r == NULL) { if (r == NULL) {
seg->ds.shm_nattch--; seg->ds.shm_nattch--;
...@@ -555,10 +565,10 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg) ...@@ -555,10 +565,10 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg)
return (VOID *)-1; return (VOID *)-1;
} }
r->shmid = shmid; r->shmid = shmid;//把ID给线性区的shmid
r->regionFlags |= VM_MAP_REGION_FLAG_SHM; r->regionFlags |= VM_MAP_REGION_FLAG_SHM;//这是一个共享线性区
seg->ds.shm_atime = time(NULL); seg->ds.shm_atime = time(NULL);//访问时间
seg->ds.shm_lpid = LOS_GetCurrProcessID(); seg->ds.shm_lpid = LOS_GetCurrProcessID();//进程ID
SYSV_SHM_UNLOCK(); SYSV_SHM_UNLOCK();
return (VOID *)(UINTPTR)r->range.base; return (VOID *)(UINTPTR)r->range.base;
...@@ -568,7 +578,7 @@ ERROR: ...@@ -568,7 +578,7 @@ ERROR:
PRINT_DEBUG("%s %d, ret = %d\n", __FUNCTION__, __LINE__, ret); PRINT_DEBUG("%s %d, ret = %d\n", __FUNCTION__, __LINE__, ret);
return (VOID *)-1; return (VOID *)-1;
} }
//此函数可以对shmid指定的共享存储进行多种操作（删除、取信息、加锁、解锁等）
INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf)
{ {
struct shmIDSource *seg = NULL; struct shmIDSource *seg = NULL;
...@@ -595,13 +605,13 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) ...@@ -595,13 +605,13 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf)
switch (cmd) { switch (cmd) {
case IPC_STAT: case IPC_STAT:
case SHM_STAT: case SHM_STAT://取段结构
ret = ShmPermCheck(seg, SHM_R); ret = ShmPermCheck(seg, SHM_R);
if (ret != 0) { if (ret != 0) {
goto ERROR; goto ERROR;
} }
ret = LOS_ArchCopyToUser(buf, &seg->ds, sizeof(struct shmid_ds)); ret = LOS_ArchCopyToUser(buf, &seg->ds, sizeof(struct shmid_ds));//把内核空间的共享页数据拷贝到用户空间
if (ret != 0) { if (ret != 0) {
ret = EFAULT; ret = EFAULT;
goto ERROR; goto ERROR;
...@@ -610,13 +620,13 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) ...@@ -610,13 +620,13 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf)
ret = (unsigned int)((unsigned int)seg->ds.shm_perm.seq << 16) | (unsigned int)((unsigned int)shmid & 0xffff); /* 16: use the seq as the upper 16 bits */ ret = (unsigned int)((unsigned int)seg->ds.shm_perm.seq << 16) | (unsigned int)((unsigned int)shmid & 0xffff); /* 16: use the seq as the upper 16 bits */
} }
break; break;
case IPC_SET: case IPC_SET://重置共享段
ret = ShmPermCheck(seg, SHM_M); ret = ShmPermCheck(seg, SHM_M);
if (ret != 0) { if (ret != 0) {
ret = EPERM; ret = EPERM;
goto ERROR; goto ERROR;
} }
//从用户空间拷贝数据到内核空间
ret = LOS_ArchCopyFromUser(&shm_perm, &buf->shm_perm, sizeof(struct ipc_perm)); ret = LOS_ArchCopyFromUser(&shm_perm, &buf->shm_perm, sizeof(struct ipc_perm));
if (ret != 0) { if (ret != 0) {
ret = EFAULT; ret = EFAULT;
...@@ -625,10 +635,10 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) ...@@ -625,10 +635,10 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf)
seg->ds.shm_perm.uid = shm_perm.uid; seg->ds.shm_perm.uid = shm_perm.uid;
seg->ds.shm_perm.gid = shm_perm.gid; seg->ds.shm_perm.gid = shm_perm.gid;
seg->ds.shm_perm.mode = (seg->ds.shm_perm.mode & ~ACCESSPERMS) | seg->ds.shm_perm.mode = (seg->ds.shm_perm.mode & ~ACCESSPERMS) |
(shm_perm.mode & ACCESSPERMS); (shm_perm.mode & ACCESSPERMS);//可访问
seg->ds.shm_ctime = time(NULL); seg->ds.shm_ctime = time(NULL);
break; break;
case IPC_RMID: case IPC_RMID://删除共享段
ret = ShmPermCheck(seg, SHM_M); ret = ShmPermCheck(seg, SHM_M);
if (ret != 0) { if (ret != 0) {
ret = EPERM; ret = EPERM;
...@@ -636,11 +646,11 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) ...@@ -636,11 +646,11 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf)
} }
seg->status |= SHM_SEG_REMOVE; seg->status |= SHM_SEG_REMOVE;
if (seg->ds.shm_nattch <= 0) { if (seg->ds.shm_nattch <= 0) {//没有任何进程在使用了
ShmFreeSeg(seg); ShmFreeSeg(seg);//释放 归还内存
} }
break; break;
case IPC_INFO: case IPC_INFO://把内核空间的共享页数据拷贝到用户空间
ret = LOS_ArchCopyToUser(buf, &g_shmInfo, sizeof(struct shminfo)); ret = LOS_ArchCopyToUser(buf, &g_shmInfo, sizeof(struct shminfo));
if (ret != 0) { if (ret != 0) {
ret = EFAULT; ret = EFAULT;
...@@ -655,7 +665,7 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) ...@@ -655,7 +665,7 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf)
shmInfo.swap_attempts = 0; shmInfo.swap_attempts = 0;
shmInfo.swap_successes = 0; shmInfo.swap_successes = 0;
shmInfo.used_ids = ShmSegUsedCount(); shmInfo.used_ids = ShmSegUsedCount();
ret = LOS_ArchCopyToUser(buf, &shmInfo, sizeof(struct shm_info)); ret = LOS_ArchCopyToUser(buf, &shmInfo, sizeof(struct shm_info));//把内核空间的共享页数据拷贝到用户空间
if (ret != 0) { if (ret != 0) {
ret = EFAULT; ret = EFAULT;
goto ERROR; goto ERROR;
...@@ -677,56 +687,60 @@ ERROR: ...@@ -677,56 +687,60 @@ ERROR:
PRINT_DEBUG("%s %d, ret = %d\n", __FUNCTION__, __LINE__, ret); PRINT_DEBUG("%s %d, ret = %d\n", __FUNCTION__, __LINE__, ret);
return -1; return -1;
} }
/* 当对共享存储的操作已经结束时，则调用shmdt与该存储段分离
如果shmat成功执行，那么内核将使与该共享存储相关的shmid_ds结构中的shm_nattch计数器值减1
注意：这并不从系统中删除共享存储的标识符以及其相关的数据结构。共享存储的仍然存在，
直至某个进程带IPC_RMID命令的调用shmctl特地删除共享存储为止
*/
INT32 ShmDt(const VOID *shmaddr) INT32 ShmDt(const VOID *shmaddr)
{ {
LosVmSpace *space = OsCurrProcessGet()->vmSpace; LosVmSpace *space = OsCurrProcessGet()->vmSpace;//获取进程空间
struct shmIDSource *seg = NULL; struct shmIDSource *seg = NULL;
LosVmMapRegion *region = NULL; LosVmMapRegion *region = NULL;
INT32 shmid; INT32 shmid;
INT32 ret; INT32 ret;
if (IS_PAGE_ALIGNED(shmaddr) == 0) { if (IS_PAGE_ALIGNED(shmaddr) == 0) {//地址是否对齐
ret = EINVAL; ret = EINVAL;
goto ERROR; goto ERROR;
} }
(VOID)LOS_MuxAcquire(&space->regionMux); (VOID)LOS_MuxAcquire(&space->regionMux);
region = LOS_RegionFind(space, (VADDR_T)(UINTPTR)shmaddr); region = LOS_RegionFind(space, (VADDR_T)(UINTPTR)shmaddr);//找到线性区
if (region == NULL) { if (region == NULL) {
ret = EINVAL; ret = EINVAL;
goto ERROR_WITH_LOCK; goto ERROR_WITH_LOCK;
} }
shmid = region->shmid; shmid = region->shmid;//线性区共享ID
if (region->range.base != (VADDR_T)(UINTPTR)shmaddr) { if (region->range.base != (VADDR_T)(UINTPTR)shmaddr) {//这是用户空间和内核空间的一次解绑
ret = EINVAL; ret = EINVAL; //shmaddr 必须要等于region->range.base
goto ERROR_WITH_LOCK; goto ERROR_WITH_LOCK;
} }
/* remove it from aspace */ /* remove it from aspace */
LOS_RbDelNode(&space->regionRbTree, &region->rbNode); LOS_RbDelNode(&space->regionRbTree, &region->rbNode);//从红黑树和链表中摘除节点
LOS_ArchMmuUnmap(&space->archMmu, region->range.base, region->range.size >> PAGE_SHIFT); LOS_ArchMmuUnmap(&space->archMmu, region->range.base, region->range.size >> PAGE_SHIFT);//解除线性区的映射
/* free it */ /* free it */
free(region); free(region);//规划线性区所占内存池中的内存
SYSV_SHM_LOCK(); SYSV_SHM_LOCK();
seg = ShmFindSeg(shmid); seg = ShmFindSeg(shmid);//找到seg,线性区和共享段的关系是 1:N 的关系,其他空间的线性区也会绑在共享段上
if (seg == NULL) { if (seg == NULL) {
ret = EINVAL; ret = EINVAL;
SYSV_SHM_UNLOCK(); SYSV_SHM_UNLOCK();
goto ERROR_WITH_LOCK; goto ERROR_WITH_LOCK;
} }
ShmPagesRefDec(seg); ShmPagesRefDec(seg);//页面引用数 --
seg->ds.shm_nattch--; seg->ds.shm_nattch--;//使用共享内存的进程数少了一个
if ((seg->ds.shm_nattch <= 0) && if ((seg->ds.shm_nattch <= 0) && //无任何进程使用共享内存
(seg->status & SHM_SEG_REMOVE)) { (seg->status & SHM_SEG_REMOVE)) {//状态为删除时需要释放 物理页内存了,否则其他进程还要继续使用共享内存
ShmFreeSeg(seg); ShmFreeSeg(seg);//释放seg 页框链表中的页框内存,再重置seg状态
} }
seg->ds.shm_dtime = time(NULL); seg->ds.shm_dtime = time(NULL);
seg->ds.shm_lpid = LOS_GetCurrProcessID(); seg->ds.shm_lpid = LOS_GetCurrProcessID();//获取当前进程ID
SYSV_SHM_UNLOCK(); SYSV_SHM_UNLOCK();
(VOID)LOS_MuxRelease(&space->regionMux); (VOID)LOS_MuxRelease(&space->regionMux);
return 0; return 0;
......
Markdown is supported
0% 或 .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑！
想要评论请 注册 或