diff options
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/base.c | 21 | ||||
| -rw-r--r-- | fs/proc/vmcore.c | 105 |
2 files changed, 85 insertions, 41 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 1f394095eb88..13eda8de2998 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1982,19 +1982,21 @@ static int pid_revalidate(struct dentry *dentry, unsigned int flags) { struct inode *inode; struct task_struct *task; + int ret = 0; - if (flags & LOOKUP_RCU) - return -ECHILD; - - inode = d_inode(dentry); - task = get_proc_task(inode); + rcu_read_lock(); + inode = d_inode_rcu(dentry); + if (!inode) + goto out; + task = pid_task(proc_pid(inode), PIDTYPE_PID); if (task) { pid_update_inode(task, inode); - put_task_struct(task); - return 1; + ret = 1; } - return 0; +out: + rcu_read_unlock(); + return ret; } static inline bool proc_inode_is_dead(struct inode *inode) @@ -3802,7 +3804,10 @@ static int proc_task_readdir(struct file *file, struct dir_context *ctx) task = next_tid(task), ctx->pos++) { char name[10 + 1]; unsigned int len; + tid = task_pid_nr_ns(task, ns); + if (!tid) + continue; /* The task has just exited. */ len = snprintf(name, sizeof(name), "%u", tid); if (!proc_fill_cache(file, ctx, name, len, proc_task_instantiate, task, NULL)) { diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index cdbbf819d2d6..30a3b66f475a 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -62,46 +62,75 @@ core_param(novmcoredd, vmcoredd_disabled, bool, 0); /* Device Dump Size */ static size_t vmcoredd_orig_sz; -/* - * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error - * The called function has to take care of module refcounting. - */ -static int (*oldmem_pfn_is_ram)(unsigned long pfn); - -int register_oldmem_pfn_is_ram(int (*fn)(unsigned long pfn)) +static DECLARE_RWSEM(vmcore_cb_rwsem); +/* List of registered vmcore callbacks. */ +static LIST_HEAD(vmcore_cb_list); +/* Whether we had a surprise unregistration of a callback. */ +static bool vmcore_cb_unstable; +/* Whether the vmcore has been opened once. */ +static bool vmcore_opened; + +void register_vmcore_cb(struct vmcore_cb *cb) { - if (oldmem_pfn_is_ram) - return -EBUSY; - oldmem_pfn_is_ram = fn; - return 0; + down_write(&vmcore_cb_rwsem); + INIT_LIST_HEAD(&cb->next); + list_add_tail(&cb->next, &vmcore_cb_list); + /* + * Registering a vmcore callback after the vmcore was opened is + * very unusual (e.g., manual driver loading). + */ + if (vmcore_opened) + pr_warn_once("Unexpected vmcore callback registration\n"); + up_write(&vmcore_cb_rwsem); } -EXPORT_SYMBOL_GPL(register_oldmem_pfn_is_ram); +EXPORT_SYMBOL_GPL(register_vmcore_cb); -void unregister_oldmem_pfn_is_ram(void) +void unregister_vmcore_cb(struct vmcore_cb *cb) { - oldmem_pfn_is_ram = NULL; - wmb(); + down_write(&vmcore_cb_rwsem); + list_del(&cb->next); + /* + * Unregistering a vmcore callback after the vmcore was opened is + * very unusual (e.g., forced driver removal), but we cannot stop + * unregistering. + */ + if (vmcore_opened) { + pr_warn_once("Unexpected vmcore callback unregistration\n"); + vmcore_cb_unstable = true; + } + up_write(&vmcore_cb_rwsem); } -EXPORT_SYMBOL_GPL(unregister_oldmem_pfn_is_ram); +EXPORT_SYMBOL_GPL(unregister_vmcore_cb); -static int pfn_is_ram(unsigned long pfn) +static bool pfn_is_ram(unsigned long pfn) { - int (*fn)(unsigned long pfn); - /* pfn is ram unless fn() checks pagetype */ - int ret = 1; + struct vmcore_cb *cb; + bool ret = true; - /* - * Ask hypervisor if the pfn is really ram. - * A ballooned page contains no data and reading from such a page - * will cause high load in the hypervisor. - */ - fn = oldmem_pfn_is_ram; - if (fn) - ret = fn(pfn); + lockdep_assert_held_read(&vmcore_cb_rwsem); + if (unlikely(vmcore_cb_unstable)) + return false; + + list_for_each_entry(cb, &vmcore_cb_list, next) { + if (unlikely(!cb->pfn_is_ram)) + continue; + ret = cb->pfn_is_ram(cb, pfn); + if (!ret) + break; + } return ret; } +static int open_vmcore(struct inode *inode, struct file *file) +{ + down_read(&vmcore_cb_rwsem); + vmcore_opened = true; + up_read(&vmcore_cb_rwsem); + + return 0; +} + /* Reads a page from the oldmem device from given offset. */ ssize_t read_from_oldmem(char *buf, size_t count, u64 *ppos, int userbuf, @@ -117,6 +146,7 @@ ssize_t read_from_oldmem(char *buf, size_t count, offset = (unsigned long)(*ppos % PAGE_SIZE); pfn = (unsigned long)(*ppos / PAGE_SIZE); + down_read(&vmcore_cb_rwsem); do { if (count > (PAGE_SIZE - offset)) nr_bytes = PAGE_SIZE - offset; @@ -124,7 +154,7 @@ ssize_t read_from_oldmem(char *buf, size_t count, nr_bytes = count; /* If pfn is not ram, return zeros for sparse dump files */ - if (pfn_is_ram(pfn) == 0) + if (!pfn_is_ram(pfn)) memset(buf, 0, nr_bytes); else { if (encrypted) @@ -136,8 +166,10 @@ ssize_t read_from_oldmem(char *buf, size_t count, tmp = copy_oldmem_page(pfn, buf, nr_bytes, offset, userbuf); - if (tmp < 0) + if (tmp < 0) { + up_read(&vmcore_cb_rwsem); return tmp; + } } *ppos += nr_bytes; count -= nr_bytes; @@ -147,6 +179,7 @@ ssize_t read_from_oldmem(char *buf, size_t count, offset = 0; } while (count); + up_read(&vmcore_cb_rwsem); return read; } @@ -537,14 +570,19 @@ static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma, unsigned long from, unsigned long pfn, unsigned long size, pgprot_t prot) { + int ret; + /* * Check if oldmem_pfn_is_ram was registered to avoid * looping over all pages without a reason. */ - if (oldmem_pfn_is_ram) - return remap_oldmem_pfn_checked(vma, from, pfn, size, prot); + down_read(&vmcore_cb_rwsem); + if (!list_empty(&vmcore_cb_list) || vmcore_cb_unstable) + ret = remap_oldmem_pfn_checked(vma, from, pfn, size, prot); else - return remap_oldmem_pfn_range(vma, from, pfn, size, prot); + ret = remap_oldmem_pfn_range(vma, from, pfn, size, prot); + up_read(&vmcore_cb_rwsem); + return ret; } static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) @@ -668,6 +706,7 @@ static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) #endif static const struct proc_ops vmcore_proc_ops = { + .proc_open = open_vmcore, .proc_read = read_vmcore, .proc_lseek = default_llseek, .proc_mmap = mmap_vmcore, |