From 2f73237aae54130d18fb86e31e57dd41702bb2ab Mon Sep 17 00:00:00 2001 From: kuangyufei Date: Wed, 21 Oct 2020 11:58:14 +0800 Subject: [PATCH] =?UTF-8?q?=E9=B8=BF=E8=92=99=E6=BA=90=E7=A0=81=E5=88=86?= =?UTF-8?q?=E6=9E=90=E7=B3=BB=E5=88=97=E7=AF=87=20https://blog.csdn.net/ku?= =?UTF-8?q?angyufei=20https://my.oschina.net/u/3751245?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- arch/arm/arm/src/user_copy.c | 2 +- kernel/base/include/los_vm_filemap.h | 8 +- kernel/base/vm/los_vm_map.c | 2 +- kernel/base/vm/shm.c | 178 +++++++++++++++------------ {www => zzz}/git/pull.sh | 0 {www => zzz}/git/push.sh | 0 {www => zzz}/test/gcc.sh | 0 {www => zzz}/test/main.c | 0 {www => zzz}/test/main.exe | Bin {www => zzz}/test/main.s | 0 10 files changed, 102 insertions(+), 88 deletions(-) rename {www => zzz}/git/pull.sh (100%) rename {www => zzz}/git/push.sh (100%) rename {www => zzz}/test/gcc.sh (100%) rename {www => zzz}/test/main.c (100%) rename {www => zzz}/test/main.exe (100%) rename {www => zzz}/test/main.s (100%) diff --git a/arch/arm/arm/src/user_copy.c b/arch/arm/arm/src/user_copy.c index 13e23baa..01cee302 100644 --- a/arch/arm/arm/src/user_copy.c +++ b/arch/arm/arm/src/user_copy.c @@ -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) -{ +{//先判断地址是不是在用户空间 if (!LOS_IsUserAddressRange((VADDR_T)(UINTPTR)dst, len)) { return len; } diff --git a/kernel/base/include/los_vm_filemap.h b/kernel/base/include/los_vm_filemap.h index 0f3e7862..a4be848b 100644 --- a/kernel/base/include/los_vm_filemap.h +++ b/kernel/base/include/los_vm_filemap.h @@ -168,14 +168,14 @@ STATIC INLINE BOOL OsIsPageMapped(LosFilePage *page) /* The follow three functions is used to SHM module */ 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) { - 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) { return BIT_GET(page->flags, FILE_PAGE_SHARED); diff --git a/kernel/base/vm/los_vm_map.c b/kernel/base/vm/los_vm_map.c index c42aa777..2edd57a8 100644 --- a/kernel/base/vm/los_vm_map.c +++ b/kernel/base/vm/los_vm_map.c @@ -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->regionType = VM_MAP_REGION_TYPE_NONE;//未映射 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; } //通过虚拟地址查询物理地址 diff --git a/kernel/base/vm/shm.c b/kernel/base/vm/shm.c index dbc8131f..bc1e11a8 100644 --- a/kernel/base/vm/shm.c +++ b/kernel/base/vm/shm.c @@ -73,31 +73,31 @@ STATIC LosMux g_sysvShmMux; #define SHM_M 010000 #endif -#ifndef ACCESSPERMS -#define ACCESSPERMS (S_IRWXU | S_IRWXG | S_IRWXO) -#endif +#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)//文件权限值意思就是 用户,用户组,其他可读可写. +#endif //代表含义U:user G:group O:other #define SHM_GROUPE_TO_USER 3 #define SHM_OTHER_TO_USER 6 /* private structure */ struct shmSegMap { - vaddr_t vaddr; - INT32 shmID; + vaddr_t vaddr; //虚拟地址 + 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 -struct shmIDSource { - struct shmid_ds ds; - UINT32 status; - LOS_DL_LIST node; +struct shmIDSource {//共享存储结构体 + 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; //状态 SHM_SEG_FREE ... + LOS_DL_LIST node; //节点,挂vmPage }; /* private data */ STATIC struct shminfo g_shmInfo = { - .shmmax = SHM_MAX,//最大的内存segment的大小 - .shmmin = SHM_MIN,//最小的内存segment的大小 - .shmmni = SHM_MNI,//整个系统的内存segment的总个数 - .shmseg = SHM_SEG,//每个进程可以使用的内存segment的最大个数 + .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 1M + .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 128 .shmall = SHM_ALL, }; @@ -113,38 +113,38 @@ INT32 ShmInit(VOID) 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) { (VOID)LOS_MuxDestroy(&g_sysvShmMux); return -1; } (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++) { - g_shmSegs[i].status = SHM_SEG_FREE; - g_shmSegs[i].ds.shm_perm.seq = i + 1; - LOS_ListInit(&g_shmSegs[i].node); + 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;//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);//初始化节点 } return 0; } - +//共享内存释放初始化 INT32 ShmDeinit(VOID) { 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; - ret = LOS_MuxDestroy(&g_sysvShmMux); + ret = LOS_MuxDestroy(&g_sysvShmMux);//销毁互斥量 if (ret != LOS_OK) { return -1; } return 0; } - +//设置共享flag STATIC inline VOID ShmSetSharedFlag(struct shmIDSource *seg) { LosVmPage *page = NULL; @@ -162,7 +162,7 @@ STATIC inline VOID ShmClearSharedFlag(struct shmIDSource *seg) OsCleanPageShared(page); } } - +//seg下所有共享页引用减少 STATIC VOID ShmPagesRefDec(struct shmIDSource *seg) { LosVmPage *page = NULL; @@ -171,7 +171,7 @@ STATIC VOID ShmPagesRefDec(struct shmIDSource *seg) LOS_AtomicDec(&page->refCounts); } } - +//分配共享页 STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg) { INT32 i; @@ -186,9 +186,9 @@ STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg) size = LOS_Align(size, PAGE_SIZE); for (i = 0; i < g_shmInfo.shmmni; i++) { - if (g_shmSegs[i].status & SHM_SEG_FREE) { - g_shmSegs[i].status &= ~SHM_SEG_FREE; - segNum = i; + if (g_shmSegs[i].status & SHM_SEG_FREE) {//找到空闲段 + g_shmSegs[i].status &= ~SHM_SEG_FREE;//变成非空闲状态 + segNum = i;//标号 break; } } @@ -198,15 +198,15 @@ STATIC INT32 ShmAllocSeg(key_t key, size_t size, int shmflg) } seg = &g_shmSegs[segNum]; - count = LOS_PhysPagesAlloc(size >> PAGE_SHIFT, &seg->node); - if (count != (size >> PAGE_SHIFT)) { - (VOID)LOS_PhysPagesFree(&seg->node); - seg->status = SHM_SEG_FREE; + 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)) {//异常释放 + (VOID)LOS_PhysPagesFree(&seg->node);// + seg->status = SHM_SEG_FREE;//回归seg池 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.key = key; seg->ds.shm_segsz = size; @@ -270,7 +270,7 @@ STATIC INT32 ShmSegValidCheck(INT32 segNum, size_t size, int shmFalg) return segNum; } - +//通过ID找到资源 STATIC struct shmIDSource *ShmFindSeg(int shmid) { struct shmIDSource *seg = NULL; @@ -281,7 +281,7 @@ STATIC struct shmIDSource *ShmFindSeg(int 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); return NULL; } @@ -306,13 +306,13 @@ STATIC VOID ShmVmmMapping(LosVmSpace *space, LOS_DL_LIST *pageList, VADDR_T vadd va += PAGE_SIZE; } } - +//fork 一个共享线性区 VOID OsShmFork(LosVmSpace *space, LosVmMapRegion *oldRegion, LosVmMapRegion *newRegion) { struct shmIDSource *seg = NULL; 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) { SYSV_SHM_UNLOCK(); VM_ERR("shm fork failed!"); @@ -364,7 +364,7 @@ STATIC INT32 ShmSegUsedCount(VOID) } return count; } - +//共享内存权限检查 STATIC INT32 ShmPermCheck(struct shmIDSource *seg, mode_t mode) { INT32 uid = LOS_GetUserID(); @@ -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 -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 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) { @@ -466,13 +472,13 @@ INT32 ShmatParamCheck(const void *shmaddr, int shmflg) } if ((shmaddr != NULL) && !IS_PAGE_ALIGNED(shmaddr) && - ((shmflg & SHM_RND) == 0)) { + ((shmflg & SHM_RND) == 0)) {//取整 SHM_RND return EINVAL; } return 0; } - +//共享 LosVmMapRegion *ShmatVmmAlloc(struct shmIDSource *seg, const VOID *shmaddr, INT32 shmflg, UINT32 prot) { @@ -482,11 +488,11 @@ LosVmMapRegion *ShmatVmmAlloc(struct shmIDSource *seg, const VOID *shmaddr, UINT32 regionFlags; 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); - if (shmaddr == NULL) { - region = LOS_RegionAlloc(space, 0, seg->ds.shm_segsz, regionFlags, 0); - } else { + 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);//分配一个区,注意这里的虚拟地址传的是0, + } 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) { vaddr = ROUNDDOWN((VADDR_T)(UINTPTR)shmaddr, SHMLBA); } else { @@ -513,7 +519,11 @@ ERROR: (VOID)LOS_MuxRelease(&space->regionMux); 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) { INT32 ret; @@ -522,7 +532,7 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg) LosVmMapRegion *r = NULL; mode_t mode; - ret = ShmatParamCheck(shmaddr, shmflg); + ret = ShmatParamCheck(shmaddr, shmflg);//参数检查 if (ret != 0) { set_errno(ret); return (VOID *)-1; @@ -535,19 +545,19 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg) } SYSV_SHM_LOCK(); - seg = ShmFindSeg(shmid); + seg = ShmFindSeg(shmid);//找到段 if (seg == NULL) { SYSV_SHM_UNLOCK(); 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); if (ret != 0) { 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); if (r == NULL) { seg->ds.shm_nattch--; @@ -555,10 +565,10 @@ VOID *ShmAt(INT32 shmid, const VOID *shmaddr, INT32 shmflg) return (VOID *)-1; } - r->shmid = shmid; - r->regionFlags |= VM_MAP_REGION_FLAG_SHM; - seg->ds.shm_atime = time(NULL); - seg->ds.shm_lpid = LOS_GetCurrProcessID(); + r->shmid = shmid;//把ID给线性区的shmid + r->regionFlags |= VM_MAP_REGION_FLAG_SHM;//这是一个共享线性区 + seg->ds.shm_atime = time(NULL);//访问时间 + seg->ds.shm_lpid = LOS_GetCurrProcessID();//进程ID SYSV_SHM_UNLOCK(); return (VOID *)(UINTPTR)r->range.base; @@ -568,7 +578,7 @@ ERROR: PRINT_DEBUG("%s %d, ret = %d\n", __FUNCTION__, __LINE__, ret); 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) { struct shmIDSource *seg = NULL; @@ -595,13 +605,13 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) switch (cmd) { case IPC_STAT: - case SHM_STAT: + case SHM_STAT://取段结构 ret = ShmPermCheck(seg, SHM_R); if (ret != 0) { 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) { ret = EFAULT; goto ERROR; @@ -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 */ } break; - case IPC_SET: + case IPC_SET://重置共享段 ret = ShmPermCheck(seg, SHM_M); if (ret != 0) { ret = EPERM; 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)); if (ret != 0) { ret = EFAULT; @@ -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.gid = shm_perm.gid; 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); break; - case IPC_RMID: + case IPC_RMID://删除共享段 ret = ShmPermCheck(seg, SHM_M); if (ret != 0) { ret = EPERM; @@ -636,11 +646,11 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) } seg->status |= SHM_SEG_REMOVE; - if (seg->ds.shm_nattch <= 0) { - ShmFreeSeg(seg); + if (seg->ds.shm_nattch <= 0) {//没有任何进程在使用了 + ShmFreeSeg(seg);//释放 归还内存 } 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)); if (ret != 0) { ret = EFAULT; @@ -655,7 +665,7 @@ INT32 ShmCtl(INT32 shmid, INT32 cmd, struct shmid_ds *buf) shmInfo.swap_attempts = 0; shmInfo.swap_successes = 0; 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) { ret = EFAULT; goto ERROR; @@ -677,56 +687,60 @@ ERROR: PRINT_DEBUG("%s %d, ret = %d\n", __FUNCTION__, __LINE__, ret); 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) { - LosVmSpace *space = OsCurrProcessGet()->vmSpace; + LosVmSpace *space = OsCurrProcessGet()->vmSpace;//获取进程空间 struct shmIDSource *seg = NULL; LosVmMapRegion *region = NULL; INT32 shmid; INT32 ret; - if (IS_PAGE_ALIGNED(shmaddr) == 0) { + if (IS_PAGE_ALIGNED(shmaddr) == 0) {//地址是否对齐 ret = EINVAL; goto ERROR; } (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) { ret = EINVAL; goto ERROR_WITH_LOCK; } - shmid = region->shmid; + shmid = region->shmid;//线性区共享ID - if (region->range.base != (VADDR_T)(UINTPTR)shmaddr) { - ret = EINVAL; + 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; //shmaddr 必须要等于region->range.base goto ERROR_WITH_LOCK; } /* remove it from aspace */ - LOS_RbDelNode(&space->regionRbTree, ®ion->rbNode); - LOS_ArchMmuUnmap(&space->archMmu, region->range.base, region->range.size >> PAGE_SHIFT); + LOS_RbDelNode(&space->regionRbTree, ®ion->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);//解除线性区的映射 /* free it */ - free(region); + free(region);//规划线性区所占内存池中的内存 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) { ret = EINVAL; SYSV_SHM_UNLOCK(); goto ERROR_WITH_LOCK; } - ShmPagesRefDec(seg); - seg->ds.shm_nattch--; - if ((seg->ds.shm_nattch <= 0) && - (seg->status & SHM_SEG_REMOVE)) { - ShmFreeSeg(seg); + ShmPagesRefDec(seg);//页面引用数 -- + seg->ds.shm_nattch--;//使用共享内存的进程数少了一个 + if ((seg->ds.shm_nattch <= 0) && //无任何进程使用共享内存 + (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);//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_lpid = LOS_GetCurrProcessID(); + seg->ds.shm_lpid = LOS_GetCurrProcessID();//获取当前进程ID SYSV_SHM_UNLOCK(); (VOID)LOS_MuxRelease(&space->regionMux); return 0; diff --git a/www/git/pull.sh b/zzz/git/pull.sh similarity index 100% rename from www/git/pull.sh rename to zzz/git/pull.sh diff --git a/www/git/push.sh b/zzz/git/push.sh similarity index 100% rename from www/git/push.sh rename to zzz/git/push.sh diff --git a/www/test/gcc.sh b/zzz/test/gcc.sh similarity index 100% rename from www/test/gcc.sh rename to zzz/test/gcc.sh diff --git a/www/test/main.c b/zzz/test/main.c similarity index 100% rename from www/test/main.c rename to zzz/test/main.c diff --git a/www/test/main.exe b/zzz/test/main.exe similarity index 100% rename from www/test/main.exe rename to zzz/test/main.exe diff --git a/www/test/main.s b/zzz/test/main.s similarity index 100% rename from www/test/main.s rename to zzz/test/main.s -- GitLab