• Marc Zyngier's avatar
    genirq: Add irq_domain-aware core IRQ handler · 76ba59f8
    Marc Zyngier authored
    Calling irq_find_mapping from outside a irq_{enter,exit} section is
    unsafe and produces ugly messages if CONFIG_PROVE_RCU is enabled:
    If coming from the idle state, the rcu_read_lock call in irq_find_mapping
    will generate an unpleasant warning:
    
    <quote>
    ===============================
    [ INFO: suspicious RCU usage. ]
    3.16.0-rc1+ #135 Not tainted
    -------------------------------
    include/linux/rcupdate.h:871 rcu_read_lock() used illegally while idle!
    
    other info that might help us debug this:
    
    RCU used illegally from idle CPU!
    rcu_scheduler_active = 1, debug_locks = 0
    RCU used illegally from extended quiescent state!
    1 lock held by swapper/0/0:
     #0:  (rcu_read_lock){......}, at: [<ffffffc00010206c>]
    irq_find_mapping+0x4c/0x198
    </quote>
    
    As this issue is fairly widespread and involves at least three
    different architectures, a possible solution is to add a new
    handle_domain_irq entry point into the generic IRQ code that
    the interrupt controller code can call.
    
    This new function takes an irq_domain, and calls into irq_find_domain
    inside the irq_{enter,exit} block. An additional "lookup" parameter is
    used to allow non-domain architecture code to be replaced by this as well.
    
    Interrupt controllers can then be updated to use the new mechanism.
    
    This code is sitting behind a new CONFIG_HANDLE_DOMAIN_IRQ, as not all
    architectures implement set_irq_regs (yes, mn10300, I'm looking at you...).
    Reported-by: default avatarVladimir Murzin <vladimir.murzin@arm.com>
    Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
    Link: https://lkml.kernel.org/r/1409047421-27649-2-git-send-email-marc.zyngier@arm.comSigned-off-by: default avatarJason Cooper <jason@lakedaemon.net>
    76ba59f8
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