lkml.org 
[lkml]   [2013]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[ 093/100] efivars: Disable external interrupt while holding efivars->lock
    Date
    3.8-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Seiji Aguchi <seiji.aguchi@hds.com>

    commit 81fa4e581d9283f7992a0d8c534bb141eb840a14 upstream.

    [Problem]
    There is a scenario which efi_pstore fails to log messages in a panic case.

    - CPUA holds an efi_var->lock in either efivarfs parts
    or efi_pstore with interrupt enabled.
    - CPUB panics and sends IPI to CPUA in smp_send_stop().
    - CPUA stops with holding the lock.
    - CPUB kicks efi_pstore_write() via kmsg_dump(KSMG_DUMP_PANIC)
    but it returns without logging messages.

    [Patch Description]
    This patch disables an external interruption while holding efivars->lock
    as follows.

    In efi_pstore_write() and get_var_data(), spin_lock/spin_unlock is
    replaced by spin_lock_irqsave/spin_unlock_irqrestore because they may
    be called in an interrupt context.

    In other functions, they are replaced by spin_lock_irq/spin_unlock_irq.
    because they are all called from a process context.

    By applying this patch, we can avoid the problem above with
    a following senario.

    - CPUA holds an efi_var->lock with interrupt disabled.
    - CPUB panics and sends IPI to CPUA in smp_send_stop().
    - CPUA receives the IPI after releasing the lock because it is
    disabling interrupt while holding the lock.
    - CPUB waits for one sec until CPUA releases the lock.
    - CPUB kicks efi_pstore_write() via kmsg_dump(KSMG_DUMP_PANIC)
    And it can hold the lock successfully.

    Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
    Acked-by: Mike Waychison <mikew@google.com>
    Acked-by: Matt Fleming <matt.fleming@intel.com>
    Signed-off-by: Tony Luck <tony.luck@intel.com>
    Cc: Josh Boyer <jwboyer@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


    ---
    drivers/firmware/efivars.c | 84 +++++++++++++++++++++++----------------------
    1 file changed, 43 insertions(+), 41 deletions(-)

    --- a/drivers/firmware/efivars.c
    +++ b/drivers/firmware/efivars.c
    @@ -406,10 +406,11 @@ static efi_status_t
    get_var_data(struct efivars *efivars, struct efi_variable *var)
    {
    efi_status_t status;
    + unsigned long flags;

    - spin_lock(&efivars->lock);
    + spin_lock_irqsave(&efivars->lock, flags);
    status = get_var_data_locked(efivars, var);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irqrestore(&efivars->lock, flags);

    if (status != EFI_SUCCESS) {
    printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
    @@ -538,14 +539,14 @@ efivar_store_raw(struct efivar_entry *en
    return -EINVAL;
    }

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);
    status = efivars->ops->set_variable(new_var->VariableName,
    &new_var->VendorGuid,
    new_var->Attributes,
    new_var->DataSize,
    new_var->Data);

    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);

    if (status != EFI_SUCCESS) {
    printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
    @@ -714,7 +715,7 @@ static ssize_t efivarfs_file_write(struc
    * amounts of memory. Pick a default size of 64K if
    * QueryVariableInfo() isn't supported by the firmware.
    */
    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);

    if (!efivars->ops->query_variable_info)
    status = EFI_UNSUPPORTED;
    @@ -724,7 +725,7 @@ static ssize_t efivarfs_file_write(struc
    &remaining_size, &max_size);
    }

    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);

    if (status != EFI_SUCCESS) {
    if (status != EFI_UNSUPPORTED)
    @@ -755,7 +756,7 @@ static ssize_t efivarfs_file_write(struc
    * set_variable call, and removal of the variable from the efivars
    * list (in the case of an authenticated delete).
    */
    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);

    status = efivars->ops->set_variable(var->var.VariableName,
    &var->var.VendorGuid,
    @@ -763,7 +764,7 @@ static ssize_t efivarfs_file_write(struc
    data);

    if (status != EFI_SUCCESS) {
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    kfree(data);

    return efi_status_to_err(status);
    @@ -784,21 +785,21 @@ static ssize_t efivarfs_file_write(struc
    NULL);

    if (status == EFI_BUFFER_TOO_SMALL) {
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    mutex_lock(&inode->i_mutex);
    i_size_write(inode, newdatasize + sizeof(attributes));
    mutex_unlock(&inode->i_mutex);

    } else if (status == EFI_NOT_FOUND) {
    list_del(&var->list);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    efivar_unregister(var);
    drop_nlink(inode);
    d_delete(file->f_dentry);
    dput(file->f_dentry);

    } else {
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    pr_warn("efivarfs: inconsistent EFI variable implementation? "
    "status = %lx\n", status);
    }
    @@ -820,11 +821,11 @@ static ssize_t efivarfs_file_read(struct
    void *data;
    ssize_t size = 0;

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);
    status = efivars->ops->get_variable(var->var.VariableName,
    &var->var.VendorGuid,
    &attributes, &datasize, NULL);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);

    if (status != EFI_BUFFER_TOO_SMALL)
    return efi_status_to_err(status);
    @@ -834,12 +835,12 @@ static ssize_t efivarfs_file_read(struct
    if (!data)
    return -ENOMEM;

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);
    status = efivars->ops->get_variable(var->var.VariableName,
    &var->var.VendorGuid,
    &attributes, &datasize,
    (data + sizeof(attributes)));
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);

    if (status != EFI_SUCCESS) {
    size = efi_status_to_err(status);
    @@ -1005,9 +1006,9 @@ static int efivarfs_create(struct inode
    goto out;

    kobject_uevent(&var->kobj, KOBJ_ADD);
    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);
    list_add(&var->list, &efivars->list);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    d_instantiate(dentry, inode);
    dget(dentry);
    out:
    @@ -1024,7 +1025,7 @@ static int efivarfs_unlink(struct inode
    struct efivars *efivars = var->efivars;
    efi_status_t status;

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);

    status = efivars->ops->set_variable(var->var.VariableName,
    &var->var.VendorGuid,
    @@ -1032,14 +1033,14 @@ static int efivarfs_unlink(struct inode

    if (status == EFI_SUCCESS || status == EFI_NOT_FOUND) {
    list_del(&var->list);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    efivar_unregister(var);
    drop_nlink(dentry->d_inode);
    dput(dentry);
    return 0;
    }

    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    return -EINVAL;
    };

    @@ -1194,13 +1195,13 @@ static int efivarfs_fill_super(struct su
    /* copied by the above to local storage in the dentry. */
    kfree(name);

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);
    efivars->ops->get_variable(entry->var.VariableName,
    &entry->var.VendorGuid,
    &entry->var.Attributes,
    &size,
    NULL);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);

    mutex_lock(&inode->i_mutex);
    inode->i_private = entry;
    @@ -1263,7 +1264,7 @@ static int efi_pstore_open(struct pstore
    {
    struct efivars *efivars = psi->data;

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);
    efivars->walk_entry = list_first_entry(&efivars->list,
    struct efivar_entry, list);
    return 0;
    @@ -1273,7 +1274,7 @@ static int efi_pstore_close(struct pstor
    {
    struct efivars *efivars = psi->data;

    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    return 0;
    }

    @@ -1349,8 +1350,9 @@ static int efi_pstore_write(enum pstore_
    int i, ret = 0;
    u64 storage_space, remaining_space, max_variable_size;
    efi_status_t status = EFI_NOT_FOUND;
    + unsigned long flags;

    - spin_lock(&efivars->lock);
    + spin_lock_irqsave(&efivars->lock, flags);

    /*
    * Check if there is a space enough to log.
    @@ -1362,7 +1364,7 @@ static int efi_pstore_write(enum pstore_
    &remaining_space,
    &max_variable_size);
    if (status || remaining_space < size + DUMP_NAME_LEN * 2) {
    - spin_unlock(&efivars->lock);
    + spin_unlock_irqrestore(&efivars->lock, flags);
    *id = part;
    return -ENOSPC;
    }
    @@ -1376,7 +1378,7 @@ static int efi_pstore_write(enum pstore_
    efivars->ops->set_variable(efi_name, &vendor, PSTORE_EFI_ATTRIBUTES,
    size, psi->buf);

    - spin_unlock(&efivars->lock);
    + spin_unlock_irqrestore(&efivars->lock, flags);

    if (size)
    ret = efivar_create_sysfs_entry(efivars,
    @@ -1403,7 +1405,7 @@ static int efi_pstore_erase(enum pstore_
    sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count,
    time.tv_sec);

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);

    for (i = 0; i < DUMP_NAME_LEN; i++)
    efi_name[i] = name[i];
    @@ -1447,7 +1449,7 @@ static int efi_pstore_erase(enum pstore_
    if (found)
    list_del(&found->list);

    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);

    if (found)
    efivar_unregister(found);
    @@ -1517,7 +1519,7 @@ static ssize_t efivar_create(struct file
    return -EINVAL;
    }

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);

    /*
    * Does this variable already exist?
    @@ -1535,7 +1537,7 @@ static ssize_t efivar_create(struct file
    }
    }
    if (found) {
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    return -EINVAL;
    }

    @@ -1549,10 +1551,10 @@ static ssize_t efivar_create(struct file
    if (status != EFI_SUCCESS) {
    printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
    status);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    return -EIO;
    }
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);

    /* Create the entry in sysfs. Locking is not required here */
    status = efivar_create_sysfs_entry(efivars,
    @@ -1580,7 +1582,7 @@ static ssize_t efivar_delete(struct file
    if (!capable(CAP_SYS_ADMIN))
    return -EACCES;

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);

    /*
    * Does this variable already exist?
    @@ -1598,7 +1600,7 @@ static ssize_t efivar_delete(struct file
    }
    }
    if (!found) {
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    return -EINVAL;
    }
    /* force the Attributes/DataSize to 0 to ensure deletion */
    @@ -1614,12 +1616,12 @@ static ssize_t efivar_delete(struct file
    if (status != EFI_SUCCESS) {
    printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
    status);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    return -EIO;
    }
    list_del(&search_efivar->list);
    /* We need to release this lock before unregistering. */
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    efivar_unregister(search_efivar);

    /* It's dead Jim.... */
    @@ -1734,9 +1736,9 @@ efivar_create_sysfs_entry(struct efivars
    kfree(short_name);
    short_name = NULL;

    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);
    list_add(&new_efivar->list, &efivars->list);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);

    return 0;
    }
    @@ -1805,9 +1807,9 @@ void unregister_efivars(struct efivars *
    struct efivar_entry *entry, *n;

    list_for_each_entry_safe(entry, n, &efivars->list, list) {
    - spin_lock(&efivars->lock);
    + spin_lock_irq(&efivars->lock);
    list_del(&entry->list);
    - spin_unlock(&efivars->lock);
    + spin_unlock_irq(&efivars->lock);
    efivar_unregister(entry);
    }
    if (efivars->new_var)



    \
     
     \ /
      Last update: 2013-03-13 01:41    [W:4.151 / U:1.096 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site