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    Subject[PATCH 3/3] pstore: add 'rmmod ramoops' support
    Date
    ramoops doesn't support unregistering yet, it was marked as TODO.
    This patch adds some code to fix it:
    1) Add functions to unregister kmsg/console/ftrace/pmsg.
    2) Add a function to free compression buffer.
    3) Remove try_module_get() to allow this module can be unloaded.
    4) Unmap the memory and free it.
    5) Set console flags, make sure it can be registered again after
    be unregistered.

    Signed-off-by: Geliang Tang <geliangtang@163.com>
    ---
    fs/pstore/ftrace.c | 15 ++++++++++++++-
    fs/pstore/internal.h | 4 ++++
    fs/pstore/platform.c | 40 ++++++++++++++++++++++++++++++++--------
    fs/pstore/pmsg.c | 7 +++++++
    fs/pstore/ram.c | 19 ++++++++-----------
    include/linux/pstore.h | 5 +++++
    6 files changed, 70 insertions(+), 20 deletions(-)

    diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c
    index 76a4eeb..554c1ce 100644
    --- a/fs/pstore/ftrace.c
    +++ b/fs/pstore/ftrace.c
    @@ -104,9 +104,10 @@ static const struct file_operations pstore_knob_fops = {
    .write = pstore_ftrace_knob_write,
    };

    +static struct dentry *dir;
    +
    void pstore_register_ftrace(void)
    {
    - struct dentry *dir;
    struct dentry *file;

    if (!psinfo->write_buf)
    @@ -129,3 +130,15 @@ void pstore_register_ftrace(void)
    err_file:
    debugfs_remove(dir);
    }
    +
    +void pstore_unregister_ftrace(void)
    +{
    + mutex_lock(&pstore_ftrace_lock);
    + if (pstore_ftrace_enabled) {
    + unregister_ftrace_function(&pstore_ftrace_ops);
    + pstore_ftrace_enabled = 0;
    + }
    + mutex_unlock(&pstore_ftrace_lock);
    +
    + debugfs_remove_recursive(dir);
    +}
    diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
    index c36ba2c..96253c4 100644
    --- a/fs/pstore/internal.h
    +++ b/fs/pstore/internal.h
    @@ -41,14 +41,18 @@ pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)

    #ifdef CONFIG_PSTORE_FTRACE
    extern void pstore_register_ftrace(void);
    +extern void pstore_unregister_ftrace(void);
    #else
    static inline void pstore_register_ftrace(void) {}
    +static inline void pstore_unregister_ftrace(void) {}
    #endif

    #ifdef CONFIG_PSTORE_PMSG
    extern void pstore_register_pmsg(void);
    +extern void pstore_unregister_pmsg(void);
    #else
    static inline void pstore_register_pmsg(void) {}
    +static inline void pstore_unregister_pmsg(void) {}
    #endif

    extern struct pstore_info *psinfo;
    diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
    index 1b11249..c474dc2 100644
    --- a/fs/pstore/platform.c
    +++ b/fs/pstore/platform.c
    @@ -237,6 +237,12 @@ static void allocate_buf_for_compression(void)

    }

    +static void free_buf_for_compression(void)
    +{
    + kfree(stream.workspace);
    + kfree(big_oops_buf);
    +}
    +
    /*
    * Called when compression fails, since the printk buffer
    * would be fetched for compression calling it again when
    @@ -358,6 +364,11 @@ static void pstore_register_kmsg(void)
    kmsg_dump_register(&pstore_dumper);
    }

    +static void pstore_unregister_kmsg(void)
    +{
    + kmsg_dump_unregister(&pstore_dumper);
    +}
    +
    #ifdef CONFIG_PSTORE_CONSOLE
    static void pstore_console_write(struct console *con, const char *s, unsigned c)
    {
    @@ -387,16 +398,22 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
    static struct console pstore_console = {
    .name = "pstore",
    .write = pstore_console_write,
    - .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
    .index = -1,
    };

    static void pstore_register_console(void)
    {
    + pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
    register_console(&pstore_console);
    }
    +
    +static void pstore_unregister_console(void)
    +{
    + unregister_console(&pstore_console);
    +}
    #else
    static void pstore_register_console(void) {}
    +static void pstore_unregister_console(void) {}
    #endif

    static int pstore_write_compat(enum pstore_type_id type,
    @@ -420,8 +437,6 @@ static int pstore_write_compat(enum pstore_type_id type,
    */
    int pstore_register(struct pstore_info *psi)
    {
    - struct module *owner = psi->owner;
    -
    if (backend && strcmp(backend, psi->name))
    return -EPERM;

    @@ -437,11 +452,6 @@ int pstore_register(struct pstore_info *psi)
    mutex_init(&psinfo->read_mutex);
    spin_unlock(&pstore_lock);

    - if (owner && !try_module_get(owner)) {
    - psinfo = NULL;
    - return -EINVAL;
    - }
    -
    allocate_buf_for_compression();

    if (pstore_is_mounted())
    @@ -473,6 +483,20 @@ int pstore_register(struct pstore_info *psi)
    }
    EXPORT_SYMBOL_GPL(pstore_register);

    +void pstore_unregister(void)
    +{
    + pstore_unregister_pmsg();
    + pstore_unregister_ftrace();
    + pstore_unregister_console();
    + pstore_unregister_kmsg();
    +
    + free_buf_for_compression();
    +
    + psinfo = NULL;
    + backend = NULL;
    +}
    +EXPORT_SYMBOL_GPL(pstore_unregister);
    +
    /*
    * Read all the records from the persistent store. Create
    * files in our filesystem. Don't warn about -EEXIST errors
    diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c
    index 5a2f05a..7de20cd 100644
    --- a/fs/pstore/pmsg.c
    +++ b/fs/pstore/pmsg.c
    @@ -114,3 +114,10 @@ err_class:
    err:
    return;
    }
    +
    +void pstore_unregister_pmsg(void)
    +{
    + device_destroy(pmsg_class, MKDEV(pmsg_major, 0));
    + class_destroy(pmsg_class);
    + unregister_chrdev(pmsg_major, PMSG_NAME);
    +}
    diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
    index 6c26c4d..d938bc1 100644
    --- a/fs/pstore/ram.c
    +++ b/fs/pstore/ram.c
    @@ -580,28 +580,25 @@ fail_out:

    static int __exit ramoops_remove(struct platform_device *pdev)
    {
    -#if 0
    - /* TODO(kees): We cannot unload ramoops since pstore doesn't support
    - * unregistering yet.
    - */
    struct ramoops_context *cxt = &oops_cxt;

    - iounmap(cxt->virt_addr);
    - release_mem_region(cxt->phys_addr, cxt->size);
    - cxt->max_dump_cnt = 0;
    + pstore_unregister();

    - /* TODO(kees): When pstore supports unregistering, call it here. */
    + cxt->max_dump_cnt = 0;
    kfree(cxt->pstore.buf);
    cxt->pstore.bufsize = 0;

    + persistent_ram_free(cxt->mprz);
    + persistent_ram_free(cxt->fprz);
    + persistent_ram_free(cxt->cprz);
    + ramoops_free_przs(cxt);
    +
    return 0;
    -#endif
    - return -EBUSY;
    }

    static struct platform_driver ramoops_driver = {
    .probe = ramoops_probe,
    - .remove = __exit_p(ramoops_remove),
    + .remove = ramoops_remove,
    .driver = {
    .name = "ramoops",
    },
    diff --git a/include/linux/pstore.h b/include/linux/pstore.h
    index 8e7a25b..34e4a6d 100644
    --- a/include/linux/pstore.h
    +++ b/include/linux/pstore.h
    @@ -77,6 +77,7 @@ struct pstore_info {

    #ifdef CONFIG_PSTORE
    extern int pstore_register(struct pstore_info *);
    +extern void pstore_unregister(void);
    extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason);
    #else
    static inline int
    @@ -84,6 +85,10 @@ pstore_register(struct pstore_info *psi)
    {
    return -ENODEV;
    }
    +static inline void
    +pstore_unregister(void)
    +{
    +}
    static inline bool
    pstore_cannot_block_path(enum kmsg_dump_reason reason)
    {
    --
    2.5.0



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